1. General

What is Rohshan?

Rohshan is a sidereal Vedic astrology (Jyotisha) calculation suite. From a date, time and place it casts a Rāshi chart plus 15 further divisional charts (vargas), Vimshottari, Yogini, Chara and Navamsha dashas down to the sub-period level, Ashtakavarga, Jaimini chara karakas and arudha padas, a list of detected classical yogas, a full pañcāṅga, and a muhurta screening table showing the Moon's nakshatra transits. Charts can be saved to an account, kept private, or made public.

Is Rohshan free?

Yes. Casting a chart and reading every divisional chart, dasha system, Ashtakavarga table, yoga list and pañcāṅga is free and doesn't require an account. An account is only needed to save a chart for later or to share it publicly.

Do I need an account?

No. You can cast and fully read a chart as a guest. Sign up only if you want the chart to still be there next time you visit, or if you want to publish it to the public charts page.

Does it work on mobile?

Yes — the three charts stack into a single column and the side panel moves below the main chart area on narrow screens.

How do I report a bug or request a feature?

Use the feedback option in the interface you're using Rohshan through (for example, the thumbs-down button if you're inside a chat-based client). Every report is read.

What's on the roadmap?

Planned: full six-fold Shadbala and Vimsopaka bala, Ashtakavarga shodhana (trikona and ekadhipatya reductions), additional nakshatra-based dashas (Ashtottari, Shodashottari) and Narayana dasha, an East Indian and Sarvatobhadra chakra style, varshaphal (solar return charts), a muhurta search tool, and astrocartography.

Do you show ads?

No. Rohshan doesn't display advertising, and nobody can pay to be promoted inside the tool.

2. Using the Software

What browsers are supported?

Any current version of Chrome, Firefox, Safari or Edge. The tool is built with standard modern web technology (CSS Grid, SVG, the aspect-ratio property) that all of these support well.

What's the difference between North and South Indian chart style?

They show identical data laid out differently. In North Indian style the diamond rotates so the ascendant's sign always sits in the top house, and the numbers 1–12 move around the fixed diamond. In South Indian style the twelve sign boxes never move — Aries is always the same box — and a small marker indicates which box is currently the ascendant. Use whichever your tradition or training uses; the underlying positions are identical either way.

How do I view a different divisional chart?

The first of the three charts is fixed to D-1 (Rāshi). The second and third each have a dropdown letting you pick any of the 16 vargas independently, so you can compare, for example, D-9 and D-10 side by side with the Rāshi chart.

What does double-clicking a planet do?

It re-bases the chart to view it “from” that planet — the wheel rotates so that planet's sign becomes the 1st house, a common technique for readings such as viewing the chart from the Moon or from a significator. The true ascendant is still marked (as “As”) wherever its sign now falls; it never moves house arbitrarily. Double-click “As” itself to reset to the natural chart.

What do the arrows below each chart do?

Each divisional chart's lagna (ascendant sign in that varga) is only valid for a specific window of time — a few minutes for a fine varga like D-60, a couple of hours for D-1. The bar below each chart shows that exact window and lets you step to the previous or next lagna period, nudging the birth time just past the boundary — useful for exploring how sensitive a reading is to the exact birth time, or for rectification work.

How many cities are supported?

Over 135,000 places worldwide — everywhere GeoNames records with a population of 1,000 or more — searchable by typing a few letters of the name.

Why does the location field show "standard time" — what about daylight saving?

City coordinates come with their standard-time UTC offset (the offset used for most of the year). If the birth happened during a period when daylight saving was in effect, add 1 to the UTC offset field manually before casting — a note beneath the input card is a standing reminder of this.

What do “R” and “cb” mean next to a planet?

“R” marks a planet in apparent retrograde motion (moving backward through the zodiac as seen from Earth). “cb” marks combustion — the planet sitting too close to the Sun to be classically “visible.” Both are shown in the planetary table and, as a colour, in the charts themselves.

Why don't Rahu and Ketu show “R” in the charts?

The lunar nodes move backward through the zodiac by their very nature — they are never anything but retrograde, with vanishingly rare exceptions not modelled by the mean-node method used here. Marking every single occurrence with “R” would add visual noise without adding information, so the charts show Rahu and Ketu in the same vermilion colour used for retrograde planets, without the redundant letter. The planetary table (which has more room) still labels them clearly by name.

What is the “transit overlay” toggle?

It draws the current real-time planetary positions (as of the moment you're looking at the chart) on top of the natal chart in a contrasting blue italic, letting you see at a glance which houses are currently being transited.

How does day/night mode work?

The sun/moon icons switch the whole interface between a light, manuscript-inspired palette and a dark one. Your choice is remembered in your browser and carries across every page of the site — the workbench, Learn, this FAQ, and the login/signup pages.

3. Calculation Methodology

What ayanamsa does Rohshan use?

Chitrapaksha (Lahiri), the ayanamsa mandated by the Indian government's Calendar Reform Committee and the most widely used sidereal standard. It's computed as a secular polynomial referenced to J2000.0: ayanamsa = 23.85305° + 1.3969713°·T + 0.0003086°·T², where T is the number of Julian centuries since J2000.0 (2000 January 1, 12:00 TT). This is the value subtracted from the tropical longitude of every graha to obtain its sidereal position.

How are planetary positions calculated?

The Sun and Moon use Jean Meeus's abridged solar and lunar series from Astronomical Algorithms — closed-form trigonometric series (the lunar series carries its 30 largest periodic terms) that reproduce the full VSOP87/ELP2000 theories to within about an arc-minute without needing to evaluate thousands of terms.

Mercury, Venus, Mars, Jupiter and Saturn use Standish's J2000 mean orbital elements (semi-major axis, eccentricity, inclination, mean longitude, longitude of perihelion, longitude of ascending node, each with a linear secular rate). For a given moment, Rohshan solves Kepler's equation for each planet's true anomaly, builds its heliocentric position, does the same for Earth, and differences the two to get a geocentric ecliptic longitude, applying the same secular precession correction used for the ayanamsa so tropical and sidereal frames stay consistent.

How accurate are the positions?

The Sun and Moon are accurate to roughly 1 arc-minute; the five outer/inner tāra-grahas to a few arc-minutes. This is because the Standish elements are a two-body Keplerian approximation — they don't include planet-on-planet gravitational perturbations the way a full numerical integration (such as JPL's DE ephemerides or the Swiss Ephemeris built on them) does. For anything where a few arc-minutes could matter — muhurta selection down to the second, chart rectification, or research requiring maximum precision — cross-check the specific data point against a Swiss-Ephemeris-based source. For ordinary birth-chart reading, sign and even most nakshatra-pada placements are unaffected at this level of precision.

Does Rohshan use the mean or true lunar node for Rahu/Ketu?

The mean node — the node's smoothly-averaged position, ignoring its short-period oscillation. This is the classical and most widely used choice in Jyotisha; the mean and true node never differ by more than about 1.5°, so the choice rarely changes a sign placement and essentially never changes a house.

How are houses assigned?

Whole-sign (Rāshi) houses: the ascendant's entire sign is the 1st house, the next full sign is the 2nd, and so on — not a quadrant system like Placidus or Koch that divides houses by unequal arcs based on time. This is the house system given in Brihat Parashara Hora Shastra and used throughout the classical Parashari tradition.

How is the ascendant (lagna) calculated?

Standard spherical astronomy: Greenwich Mean Sidereal Time is computed for the birth moment, added to the geographic longitude to get the Right Ascension of the Meridian (RAMC), and combined with the obliquity of the ecliptic and the birth latitude in the classical ascendant formula (atan2 of RAMC's cosine against a combination of RAMC's sine, obliquity, and the tangent of latitude). The result is a tropical ecliptic longitude, converted to sidereal with the same ayanamsa used everywhere else.

What are Bhava Lagna, Hora Lagna, Ghatika Lagna and Gulika?

These are secondary “lagnas” computed from how far the Sun has moved since sunrise, each advancing through the zodiac at a different classical rate from the sidereal solar position at sunrise:

Gulika is the sub-lord point associated with Saturn's portion of the day or night, found by dividing the sunrise-to-sunset (or sunset-to-next-sunrise) span into 8 equal parts, identifying which part belongs to Saturn by the classical weekday-based sequence, and taking the ascendant rising at the start of that part.

What is Pranapada Lagna and how is it calculated?

Per Brihat Parashara Hora Shastra: the ishta-kāla (time elapsed since the most recent sunrise, in ghatis) advances the zodiac at 120° per ghati (one rāshi every 15 vighatis), starting from the Sun's own sidereal position — but offset differently depending on whether the Sun sits in a movable, fixed, or dual sign (added directly, counted from the 9th, or from the 5th, respectively). It's used to gauge how effectively one channels one's life-force (prana) in the world.

What is Arudha Lagna and how is it derived?

Arudha Lagna (and the corresponding pada for every other house) is found by counting from a house to its lord's sign, then counting that same number of signs again from the lord — the classical “reflection” rule. If that reflection would land back on the house itself or its 7th (the two positions the rule treats as invalid), the pada is taken from the 10th house from that position instead. Arudha represents the image the world perceives, often quite different from the reality shown by the plain Rāshi placement.

What are the Chara Karakas?

The eight-karaka scheme: the seven classical grahas (excluding the always-retrograde nodes' usual treatment) plus Rahu are ranked by their degree within their sign, from highest to lowest, and assigned the eight roles Atmakaraka (self), Amatyakaraka (career), Bhratrikaraka (siblings), Matrikaraka (mother), Pitrikaraka (father), Putrakaraka (children), Gnatikaraka (rivals) and Darakaraka (spouse) in that order. Rahu's degree is counted as 30° minus its actual degree in sign, per the standard convention for including a node in this ranking.

How are the 16 divisional charts (vargas) calculated?

Each varga divides every 30° sign into n equal (or, for a few vargas, classically unequal) parts and maps each part to a sign according to its own classical rule:

All 16 are available from the dropdown on the second and third chart; degree labels shown alongside planets in a varga view are the D-1 degree, kept for quick cross-reference against the birth chart.

How is Vimshottari Dasha calculated?

The 120-year Vimshottari cycle is the most widely used dasha system. The Moon's nakshatra at birth fixes both the starting mahadasha lord and how much of that first period has already elapsed at birth (proportional to how far the Moon has moved through that nakshatra). The nine lords — Ketu, Venus, Sun, Moon, Mars, Rahu, Jupiter, Saturn, Mercury — follow in that fixed order with fixed lengths (7, 20, 6, 10, 7, 18, 16, 19 and 17 years respectively, summing to 120). Each mahadasha subdivides into antardashas of the nine lords in the same cyclic order starting from the mahadasha lord itself, each antardasha's length proportional to its lord's overall share of 120 years; the same subdivision repeats one level deeper for pratyantardashas.

How is Yogini Dasha calculated?

An 8-yogini, 36-year cycle (Mangala, Pingala, Dhanya, Bhramari, Bhadrika, Ulka, Siddha, Sankata, with lengths 1 through 8 years). The starting yogini is fixed from the Moon's nakshatra by the classical formula (nakshatra number, counted from 1, plus 3, modulo 8), with the same elapsed-proportion logic as Vimshottari applied to the birth nakshatra. Rohshan shows two full cycles (16 mahadashas, 72 years) with antardashas subdividing each in the same cyclic 8-yogini order.

How is Chara Dasha calculated?

A Jaimini rāshi dasha (the K. N. Rao variant): the sequence of dashas runs through the 12 signs starting from the lagna, forward if the lagna is an odd sign and backward if even. Each sign's own dasha length is the count of signs from it to its lord (counting in the sign's own forward/backward direction), with Scorpio's dasha lord taken as Mars and Aquarius's as Saturn per the classical exception; a sign that lands exactly on its own lord runs a full 12 years. Each mahadasha divides into 12 equal antardashas following the same sign sequence.

How is Navamsha Dasha calculated?

A fixed 9-year-per-sign rāshi dasha starting from the Navamsha (D-9) lagna, running forward through the signs if that D-9 lagna is odd and backward if even, with 12 equal one-year antardashas inside each 9-year mahadasha.

How is Ashtakavarga calculated?

The classical BPHS bindu tables: for each of the seven grahas, eight reference points (the seven grahas plus the lagna) each contribute a bindu (point) to specific houses counted from that reference point's own position, following the fixed tables given in Brihat Parashara Hora Shastra. Summing one graha's bindus across all eight contributors, by sign, gives its Bhinnashtakavarga row; summing all seven grahas' rows together gives the Sarvashtakavarga total per sign, which totals exactly 337 points across the zodiac when unreduced. Rohshan currently shows the unreduced totals; trikona and ekadhipatya shodhana (the further classical reduction steps) are on the roadmap.

What is the “Bala” strength score, and is it full Shadbala?

No — it is explicitly not full Shadbala, and the panel says so. Classical Shadbala combines six components (Sthana, Dig, Kala, Cheshta, Naisargika and Drik bala) using shashtiamsha units and several dozen sub-rules. Rohshan's Bala score is a simplified composite of three of those ideas — dignity (60% weight), directional strength/dig bala (25%), and motion-based cheshta bala (15%), with a 15-point penalty for combustion — normalised to a 0–100 scale as a quick, visual triage tool, not a substitute for full classical Shadbala calculation.

How is planetary dignity determined?

By comparing a graha's sign against the classical tables of exaltation, debilitation, moolatrikona range, own sign, and the fixed naisargika maitri (natural friendship) tables that classify every other graha as a friend, neutral, or enemy of a given graha — the same tables used in classical Jyotisha for compound-friendship calculations.

What defines combustion?

Angular separation from the Sun below a fixed classical threshold that differs by planet (for example, roughly 10–17° depending on the graha) — the Sun itself is never marked combust.

What yogas does Rohshan detect?

Around 35 major combinations drawn from Brihat Parashara Hora Shastra, Phaladeepika and Saravali: all five Pancha Mahapurusha yogas (Ruchaka, Bhadra, Hamsa, Malavya, Sasha), Gajakesari, Budha-Aditya, Chandra-Mangala, the Moon-based Sunapha/Anapha/Durudhara/Kemadruma group, the Sun-based Vesi/Vosi/Ubhayachari group, kendra-trikona Raja yogas (naming the specific lords involved), Dharma-Karmadhipati yoga, the three Viparita Raja yogas (Harsha, Sarala, Vimala), Neecha Bhanga, every Parivartana (mutual sign exchange), Kala Sarpa, Guru-Chandala, both Grahan yogas, Angaraka, Amala, Shubha/Papa Kartari, Adhi, Vasumati, Dhana, Lakshmi and Saraswati yoga. This is the major-yoga canon, not the full breadth of yogas documented across the shastra — many finer combinations depend on planetary aspect (drishti) rather than sign conjunction, and aren't yet modelled.

What date range is supported?

Any date the Julian day calendar arithmetic covers, effectively centuries into the past or future. Precision is best within a few centuries of the year 2000, since the ayanamsa formula, obliquity of the ecliptic and the Standish planetary elements are all secular polynomials fitted around that epoch; for chart work well outside roughly 1800–2200 CE, cross-check results against a specialised long-baseline ephemeris.

Does Rohshan account for precession and nutation?

Precession, yes — it's built into both the ayanamsa's secular growth and the planetary elements' own secular rates. Nutation (the Moon-driven short-period wobble in the Earth's axis, typically under 20 arc-seconds) and stellar aberration are not separately modelled; their effect is well within the few-arc-minute accuracy already stated above.

Why do my positions differ slightly from other software?

Usually one of: a different ayanamsa (Raman, Krishnamurti and others differ from Chitrapaksha by roughly half a degree to over a degree), a different ephemeris source (full numerical integrations like Swiss Ephemeris versus the Meeus/Standish approximations used here), mean versus true node, or simple rounding. None of these should change a sign in the vast majority of charts; if a placement sits within a degree or two of a sign boundary and precision matters, cross-check with a Swiss-Ephemeris-based source.

4. Panchanga

What is a panchanga?

A traditional Indian calendar system built from both the Sun's and the Moon's positions, unlike Western calendars which track the Sun alone. “Pañcāṅga” literally means “five limbs,” referring to the five elements calculated from that Sun-Moon relationship for any given moment.

What are the five elements of a panchanga?

Rohshan's Panchanga panel shows all five, alongside the paksha (waxing/waning fortnight), how much of the current tithi/nakshatra/yoga/karana remains, sunrise and sunset, the hora and prahara, and the amanta lunar month.

How is the Hora (planetary hour) calculated?

Each day, from sunrise to the following sunrise, is divided into 24 horas — 12 across the daylight span (sunrise to sunset) and 12 across the night span (sunset to next sunrise), so daylight and night-time horas are different lengths except near the equinoxes. The lord of the very first hora of the day is the weekday's own lord; each subsequent hora passes to the next planet in the fixed classical sequence Sun→Venus→Mercury→Moon→Saturn→Jupiter→Mars, cycling back to the Sun after Mars — the traditional order in which the planetary hour lord rotates.

What is a Prahara?

A coarser division than the hora: daylight and night-time are each split into 4 equal praharas (so 8 total per full day), used in muhurta and general daily-timing contexts where hour-level precision isn't needed.

Amanta vs Purnimanta — which does Rohshan use?

Amanta — the lunar month runs new-moon to new-moon and takes its name from the sidereal solar sign occupied at that preceding new moon. This is the reckoning most common in southern and western India; Purnimanta (full-moon to full-moon, more common in the north) is not currently offered as an alternative.

5. Muhurta

What does the Muhurta tab show?

A table of the Moon's next twelve nakshatra transits from the present moment, each with the exact time it enters the next nakshatra, that nakshatra's classical “nature” category and what kind of activity suits it, and its tarabala counted from your chart's birth nakshatra.

What is Tarabala?

A nine-fold classification of how a given nakshatra relates to your birth nakshatra, counted around the 27 nakshatras in groups of nine: Janma, Sampat, Vipat, Kshema, Pratyak, Sadhana, Naidhana, Mitra and Parama Mitra. Vipat, Pratyak and Naidhana are traditionally avoided for starting new undertakings; the muhurta table marks these with a cross so they're easy to screen out at a glance.

What are the nakshatra “nature” classes?

A traditional sevenfold grouping of the 27 nakshatras by temperament — Kshipra (swift, good for quick starts), Ugra (fierce, suited to confrontation or endings), Mridu (gentle, suited to art and romance), Dhruva (fixed, suited to lasting foundations), Chara (movable, suited to travel and change), Tikshna (sharp, suited to incisive or severe acts) and Mishra (mixed). Combined with tarabala, tithi and vara, this gives a first-pass screen for muhurta selection — always cross-check against a fuller classical muhurta text for anything consequential.

6. Rohshan

What is Rohshan?

Rohshan is the astrologer built into the workbench, interpreting a chart in plain language. A crucial point: Rohshan never calculates the astrology itself. Every position, dasha, yoga and score is computed by the engine first, and Rohshan is only ever given that finished data to interpret — so its readings are grounded in the same numbers you see on screen, not invented. These features require a free account so your readings can be saved to your chart.

Ask Rohshan (chat)

A conversation box for any question about the loaded chart — career, marriage, wealth, health, a specific dasha period, a yoga, a house. Tap one of the life-area buttons (Career, Marriage & love, Wealth, Health, Spiritual path, This period) for a well-formed question in one click, or type your own. The full conversation is saved against that chart so you can return to it.

Dasha explanations

Next to each Vimshottari and Chara dasha sub-period, an “Explain in depth” button gives a two-part reading: a plain-language story of what the period tends to feel like and the kinds of events it may bring, followed by the astrological reasoning grounded in the actual placements of the period's lords. Each explanation is generated once and then cached, so revisiting it is instant and free.

Transit readings (Gochar) — from the Moon and from the Ascendant

Two readings that chart the current sky with your natal Moon sign (Chandra Lagna) or your Ascendant placed as the first house, and read each transiting planet in turn: how long it remains in its current sign, how it affects the house it occupies (weighing both the natal planets there and any other planets currently transiting it), the aspects it casts, and — importantly — an Ashtakavarga-based judgement of how favourable each placement actually is. The Moon-based view is the classical lens for how a period feels; the Ascendant-based view speaks more to outward circumstances. It ends with an overall synthesis.

Today's guidance

A short daily reading of the day's transits against your chart — the tone of the day, where to focus, and what to be patient with. Generated once per day per chart.

Yearly forecast (Varshaphal / Annual Return)

A twelve-month forecast that walks the dasha sub-periods running through the year alongside the slow-moving planets, with sections for the year at a glance, career and finances, relationships, health, and a period-by-period timeline. Generated on demand and cached for the year.

Compatibility reading

A full synastry analysis between the loaded chart and a partner's birth details. The engine computes the partner's chart and the classical 36-guna Ashtakoota (guna milan) score deterministically, and Rohshan then reads the two charts together as an astrologer would — the two Moons, Venus and Mars, Mercury and the ascendants, both seventh houses, and the doshas with any honest mitigations. Past readings are listed under the chart so you can revisit a reading you ran with any partner.

Full Life Blueprint

The most in-depth reading Rohshan offers — a complete, professional-grade report drawing on everything the engine computes: the full D1 planet-by-planet audit, all 16 divisional charts, every Jaimini karaka and arudha, Ashtakavarga, your complete Vimshottari dasha sequence from birth onward, and every classical yoga (tested for real strength, not just listed). It's organized into seven sections — Core Identity; Life Architecture & Key Yogas; Career, Public Standing & Wealth; Relationships, Marriage, Children & Parents; Health, Property & Spiritual Development; a chapter-by-chapter map of your whole life through your dasha sequence; and Practical Guidance & Remedies — delivered as a downloadable PDF.

Recommended only if you know your birth time accurate to within about 5 minutes. This report leans heavily on the exact Ascendant and Moon position throughout — a birth time that's off by more than a few minutes can shift house placements, the D60 (Shashtiamsha) chart, and dasha timing across the entire report. If you're not confident in your birth time to that precision, the shorter individual readings elsewhere in Rohshan are a better fit until you can verify it.

Because it draws on real extended reasoning across a large amount of chart data, generation takes a few minutes rather than seconds — keep the tab open while it runs.

Muhurta finder

A purely deterministic tool (no interpretation involved) that finds favourable windows in the next ~30 days for a chosen undertaking — marriage, business, travel, property, education, surgery, contracts or litigation. It screens the Moon's nakshatra transits by the nature suited to that activity and by your tarabala, and includes a legend explaining which kind of nakshatra suits which kind of work.

7. Accounts & Privacy

Are my saved charts private by default?

Yes, always. Every chart is created private; there is no way to save a chart as public by accident — making a chart visible to others is always a separate, explicit action you take afterward. This isn't just an interface choice: it's enforced by the database itself, so it holds even if a future version of the app ever had a bug in its own display logic.

Can I make a chart public?

Yes — from “My charts,” toggle any chart's lock icon to a globe icon to make it public, or back to private at any time. Public charts (and the birth data behind them) become visible to anyone who visits the Public Charts page or has the direct link — treat “public” as genuinely public, not as a quietly-shareable link.

What data does Rohshan store?

For a saved chart: the name you gave it, the birth date/time/coordinates, and whether it's private or public. Everything else shown on screen — planet positions, dashas, yogas, ashtakavarga — is recalculated fresh from that birth data each time the chart is opened, rather than stored, so that engine improvements automatically apply to charts you saved previously.

Will you sell my data?

No, and Rohshan does not show advertising or let anyone pay to be promoted inside the tool.

What happens if I delete my account?

Contact support to request account and data deletion.

8. Learning Vedic Astrology

Where do I start as a beginner?

The Learn page walks through birth charts, dashas, nakshatras, life-area readings and remedies from first principles, with a plain-language explanation alongside every technical term.

Do I need to know Sanskrit?

No. Every term Rohshan uses is explained in English wherever it first appears, both in the Learn guide and in this FAQ; the Sanskrit terms themselves are kept (rather than translated away) because that's how the tradition itself refers to them, and because translations often flatten distinctions the original terms preserve.