A bhukti is a fixed share of its dasha, and every method agrees on the share. What differs is the length of the year the shares are counted in. Hand tables use twelve months of 30 days, 360 days; Nava uses 365.25 days. That is 5.25 days a year, so the two drift apart as a dasha runs: by the end of a 20-year Venus dasha they are 105 days apart, and over the whole 120-year cycle 630 days.
☕ Same slices, different rulers
Two people cut the same ribbon into the same nine shares, but one measures with a slightly shorter ruler. Every share matches as a fraction, yet the marks drift apart along the ribbon. Bhukti dates from a hand table and from Nava differ in exactly that way.
The hand rule is quick: multiply the two lords' years and read months and days straight off the product (Jataka Parijata (tr. Subramanya Sastri), ch. XVIII, v. 61, p. 1032). It works because it counts months of 30 days, a 360-day year. Counted on Nava's year of 365.25 days instead, each bhukti of the Venus dasha ends a little later, and the gap grows bhukti by bhukti, in the card “Where each bhukti of the Venus dasha ends” below.
Sanjay Rath prints a pratyantar three levels deep, worked from a printed balance at birth (Sanjay Rath, Crux of Vedic Astrology, pp. 116–117). Run on Nava's year, both of his dates come out to the day; on a year of 360 days they miss by weeks. That fixes the year his book works in. It is a convention, not a measurement of the sky.
What Nava follows: the 365.25-day year for every dasha, bhukti and pratyantar. The 360-day year of the hand rule is not used. The shares are the books' own either way; only the dates move, by 630 days over the whole cycle. It is a choice of convention.
The gap, bhukti by bhukti
- End of Venus–Venus: day 1217.5 against day 1200, 17.5 days apart
- End of Venus–Sun: day 1582.75 against day 1560, 22.75 days apart
- End of Venus–Moon: day 2191.5 against day 2160, 31.5 days apart
- End of Venus–Mars: day 2617.63 against day 2580, 37.63 days apart
- End of Venus–Rahu: day 3713.38 against day 3660, 53.38 days apart
- End of Venus–Jupiter: day 4687.38 against day 4620, 67.38 days apart
- End of Venus–Saturn: day 5844 against day 5760, 84 days apart
- End of Venus–Mercury: day 6878.88 against day 6780, 98.88 days apart
- End of Venus–Ketu: day 7305 against day 7200, 105 days apart
- Mix-up: the two methods split a dasha differently. The shares are identical; only the length of the year they are counted in differs.
- Mix-up: the 360-day year is a mistake in the books. It is a hand-reckoning convention, and within it the shortcut is exact.
- Mix-up: the difference is a day or two. It is 5.25 days a year and keeps growing: 7305 days against 7200 for one Venus dasha.
Frequently asked questions
Which year is right?
Neither is a fact about the sky; each is a convention for counting dasha years. Nava uses 365.25 days because a fully printed set of dates in a modern book comes out to the day with it. A table worked by hand in months of 30 days is internally consistent too; it simply counts in a shorter year.
Does the year length change which bhukti I am in?
It can, and more so as life goes on. The order and the shares are the same, but the two calendars drift apart by 5.25 days for every year counted, 630 days by the end of the 120-year cycle. Early on they disagree only in the days around each change. After about 21 years the drift is as long as the shortest bhukti (108 days), so from then on the two can name different bhuktis for the same day.
Is this the same as the arc or time question for the balance at birth?
No. That question decides how much of the first dasha is left at birth; this one decides how long a year of the dasha is. The balance is on the page “Where the Dasha Starts”.
Deep dive: the hand rule, worked
The shortcut on three pairs against Nava's year, and what this builds on.
✍️ Strike the last digit
Multiply the two lords' years. Strike off the last digit: what is left is months, and three times the struck digit is days (Jataka Parijata (tr. Subramanya Sastri), ch. XVIII, v. 61, p. 1032). Months of 30 days make it exact for all 81 pairs.
- Venus–Venus: 20 × 20 = 400; strike the last digit: 40 months and 0 days, which is 1200 days. On Nava's year the same share is 1217.5 days.
- Sun–Sun: 6 × 6 = 36; strike the last digit: 3 months and 18 days, which is 108 days. On Nava's year the same share is 109.58 days.
- Saturn–Mercury: 19 × 17 = 323; strike the last digit: 32 months and 9 days, which is 969 days. On Nava's year the same share is 983.13 days.
Parashara's own worked bhukti of the Sun in the Sun is the same 108 days (Brihat Parashara Hora Shastra (Santhanam–Kapoor ed.), ch. 61, v. 1, p. 742).
🧭 What this builds on
The one rule that cuts every level of a dasha is on sub-periods down to prana; what a bhukti is, on dasha and bhukti.