Why horoscopes start with a date
A kundli is cast from a moment. Age is what you do with that moment later: “this dasha began when you were twenty-three,” “the solar return is next week,” “Saturn return is a 29-and-a-bit conversation, not a 30th-birthday party.” Rounding to completed years throws those sentences off even when the lagna is already correct.
This calculator does not compute dasha. It only makes the civil interval honest — years, leftover months, leftover days — so the next sentence in a reading has a clean number underneath it.
How the split is counted
We subtract two calendar dates, borrowing days from the previous month when the as-of day is smaller than the birth day, then borrowing 12 months from the year column if needed. Total days lived is the difference of those two civil dates in UTC midnight units, so daylight-saving shifts cannot steal or gift a day. The next birthday is the next anniversary on or after the as-of date (28 February for 29 February natives in common years).
Worked example: 15 May 1990 as of 8 September 2026
From 1990-05-15 to 2026-09-08 the civil split is 36 years, 3 months, 24 days. Total days lived: 13,265. 15 May 2026 has already passed, so the next birthday is 2027-05-15 — 249 days after 8 September.