The rising sign moves about one degree every four minutes. A divisional chart cuts each sign into equal parts, so the smaller the part, the faster its sign changes.
How long does each divisional chart hold its sign?
It depends only on how many parts the sign is cut into, and it is arithmetic rather than a measurement: a division into n parts changes sign every 120 ÷ n minutes. For the Navamsha that is 13.3 minutes. For the Shashtiamsha it is 2.
| Division | Sign lasts |
|---|---|
| Rashi — the birth chart | 2 hours |
| Hora — wealth | 1 hour |
| Drekkana — siblings | 40 min |
| Chaturthamsha — home | 30 min |
| Saptamsha — children | 17.1 min |
| Navamsha — marriage | 13.3 min |
| Dasamsha — work | 12 min |
| Dwadasamsha — parents | 10 min |
| Shodashamsha — comforts | 7.5 min |
| Vimshamsha — practice | 6 min |
| Chaturvimshamsha — learning | 5 min |
| Bhamsha — strengths | 4.4 min |
| Trimshamsha — hardship | 4 min |
| Khavedamsha — mother’s line | 3 min |
| Akshavedamsha — father’s line | 2.7 min |
| Shashtiamsha — the whole life, finely | 2 min |
Read the bottom of that table against your own certainty about your birth time. A time rounded to five minutes does not settle a Shashtiamsha sign at all.
What a realistic error actually moves
The table above says how fast each division turns. It does not say how much of a real chart moves, because that depends on how close each placement happens to sit to a boundary. So we measured it.
| Birth time out by | Divisional signs changed, of 16 | Share |
|---|---|---|
| 1 min | 2.3 | 14.6% |
| 5 min | 8.5 | 53.3% |
| 10 min | 11.2 | 69.8% |
| 30 min | 13.9 | 87.1% |
| 1 hour | 14 | 87.6% |
One minute already moves 2.3 of the 16. Ten minutes moves 11.2. An hour moves 14, and that is near the ceiling — past about half an hour the fine divisions have already shuffled and cannot shuffle further.
Does a wrong birth time change your dasha?
Hardly ever. Your Vimshottari dasha is set by the Moon's nakshatra — the 13°20′ segment it sits in — and the Moon covers only about 13° in a whole day. Ten minutes moves it roughly 5 arcminutes, which is almost never enough to cross into the next nakshatra.
0.8%
of charts change nakshatra at ten minutes
So 99.2% of the time your dasha sequence is unchanged.
4%
change it at a full hour
Even an hour out, the Moon usually stays in the same nakshatra.
69.8%
of divisional signs change at ten minutes
Against 0.8% for the nakshatra. The same error, two very different answers.
A remembered birth time spoils a Shashtiamsha and leaves your dasha sequence standing.
That asymmetry is worth carrying into how you read your own chart. If your time came from a family memory, the rashi chart, the Navamsha and the dasha are on firmer ground than anything finer. The dasha dates still shift, though — the balance of the first period depends on the Moon's exact degree, and ten minutes there can move a start date by months.
Questions people ask about birth time
How accurate does my birth time need to be for a kundli?
It depends which part you want to read. The rashi chart holds its rising sign for two hours, so a few minutes does not touch it. The Shashtiamsha changes every 2 minutes. Measured over 2,000 charts, a ten-minute error moves 11.2 of the sixteen divisional charts.
Can I get a kundli without a birth time?
Yes, minus the parts that need it. The planets are placed from the date alone, so rashi, nakshatra and the dasha sequence all work. The Ascendant and every house placement are left out rather than guessed — no noon fallback.
Does a wrong birth time change my rashi?
Rarely. Your rashi is the Moon's sign, and the Moon covers about 13° in a whole day. Ten minutes moves it roughly 5 arcminutes, so only 0.8% of charts change nakshatra — and a sign change is rarer still.
Which part of a kundli is most sensitive to birth time?
The highest divisional charts. A division into n parts changes sign every 120 ÷ n minutes, so the Shashtiamsha turns over every 2 minutes against two hours for the rashi chart. A time rounded to five minutes does not settle a Shashtiamsha sign at all.
Why does another site show a different Ascendant for me?
Usually the timezone. A birth before the rules changed needs the offset in force that year, not today's; an hour out moves the Ascendant about 15°, which is normally a whole sign. The ayanamsa and the house system can differ too.
Does a wrong birth time change my dasha?
The sequence, hardly ever — the Moon stays in its nakshatra through a ten-minute error 99.2% of the time. The dates do shift, though: the balance of the first period depends on the Moon's exact degree, so ten minutes can move a start date by months.
What this does not cover
- It measures the rising sign of each division, not every planet in it. A planet moves far slower than the Ascendant, so a wrong time shifts the houses around the planets more than the planets themselves.
- One place — Mumbai's meridian — and one timezone. The Ascendant turns at a rate that depends on latitude, so the figures move somewhat at high latitudes.
- No correction is applied, ever. Whatever you enter is treated as true. This post is about knowing which parts of a reading your own certainty can carry, not about us adjusting anything.
- An average is not your chart. If one of your placements sits half a degree from a boundary, a one-minute error moves it and no average will tell you so. The birth chart prints the degree, so you can check.