Written by the Cycella editorial team · Last reviewed September 28, 2026
Published September 28, 2026

How to track your period with the Nepali calendar (Bikram Sambat)

In Nepal, most of daily life runs on the Bikram Sambat (BS) calendar: school terms, festivals, office dates and the date your family remembers things by. So it is natural to remember your period the same way, like “my period came on Asoj 5”. But if you try to predict your next period by BS month dates, you will often be a few days off. Here is why, and a simple way to get it right.

The short answer

Count your cycle in days, not months. Your cycle is the number of days from the first day of one period to the first day of the next. Add that number of days to the first day of your last period, and you have your next expected period, in BS or English dates.

Why “same date every month” does not work in BS

The Bikram Sambat calendar used in Nepal is a solar calendar. Each month starts when the sun moves into a new zodiac sign, so BS months are not a fixed length. A BS month can have 29, 30, 31 or 32 days, and the same month can be a different length from one year to the next. Baisakh might have 31 days one year and 32 the next.

Your body does not follow the calendar. According to the NHS, the average cycle is around 28 days, and a gap between periods of 21 to 35 days is within the regular range. So even if your cycle is exactly 28 days every time, your period will fall on a different BS date each month, and the gap between “the same date” in two BS months could be anywhere from 29 to 32 days.

English (Gregorian) months have the same problem to a smaller degree, since they run 28 to 31 days. That is why doctors and period trackers count cycles in days.

How to calculate your next period, step by step

1. Write down the first day of each period. Day 1 is the first day of real bleeding, not spotting. BS dates are fine.
2. Count the days between two period start dates. That is one cycle length. If your period started on Bhadra 20 and the next on Asoj 17, and Bhadra had 31 days that year, your cycle was 11 + 17 = 28 days (11 days left in Bhadra after the 20th, plus 17 days into Asoj).
3. Average a few cycles. One cycle can be early or late because of stress, illness, travel or big changes in routine. The average of three to six cycles is a better guide.
4. Add your average to your last period’s start date. That gives your next expected period. Remember to use the real number of days in each BS month when you count forward.

Step 2 and step 4 are where mistakes happen, because you have to look up how many days each BS month has in that year. A period tracker does this counting for you, and so does our free Nepali (BS) period calculator: enter your last period in BS and it shows your next period, ovulation and fertile window in both BS and English dates.

What about ovulation and fertile days?

Ovulation usually happens about 14 days before your next period, not 14 days after your last one. So in a 28-day cycle it is around day 14, but in a 32-day cycle it is closer to day 18. The fertile window is roughly the 6 days ending on the day of ovulation.

These are estimates. They move when your cycle changes, and they are not a reliable way to avoid pregnancy. Read more in the fertile window: what it is, and why it isn’t contraception.

When a “late” period is just a long BS month

If you track by BS month dates, a period can look “late” when it is not. For example, if your period came on the 3rd of a 29-day month and your cycle is 32 days, the next one will arrive on the 6th of the following month. That is not late; it is just the month length.

A period is worth paying attention to when the number of days is outside the usual range. The NHS describes periods as irregular when the gap between them is less than 21 days or more than 35 days, and suggests seeing a doctor if your periods are irregular or last longer than 7 days. See irregular cycles: what’s normal, and when to see a doctor.

How Cycella handles Nepali dates

Cycella counts every cycle in days, so its predictions do not depend on which calendar you read them in. When you use the app in Nepali, the Today screen shows the Bikram Sambat date next to the English date. You log the first day of your period with one tap, and Cycella works out your average cycle, next period and fertile window from your own history. It works offline, needs no account, and keeps your logs on your phone.

Cycella is free on Google Play for Android. See what Cycella does for Nepal.