Free period, ovulation and due date calculators
Simple tools for working out your next period, ovulation day, fertile window and pregnancy due date. They are calculated in your browser: nothing you enter is sent or stored, and this site uses no analytics.
Next period calculator
When is my next period? Enter your last period and cycle length.
Ovulation calculator
Estimate the day you ovulate, 14 days before your next period.
Fertile window calculator
See the days when pregnancy is possible. Awareness only, not contraception.
Nepali (BS) period calculator
Enter your last period in Bikram Sambat and get results in BS and English dates.
Due date calculator
Estimate your due date, weeks pregnant and trimester dates from your last period.
Nepali (BS) due date calculator
Due date and Nepal check-up timing in BS and English dates.
Nepal baby vaccination schedule
Every vaccine from birth to 15 months, with dates from your baby's birth date.
How these calculators work
The period tools use the same rules. Your next period is your last period's first day plus your cycle length. Ovulation is estimated 14 days before the next period. The fertile window runs from 5 days before ovulation to 1 day after. These are estimates from averages, they are less reliable when cycles are irregular, and they are not a method of contraception.
The due date calculators add 280 days to the first day of your last period, adjusted for your cycle length. A due date is an estimate; the date your health worker gives you always comes first.
Cycella, a private Android period tracker, does this from your own logged cycles instead of one number you type in. It needs no account, has no ads or analytics, works offline, and is free on Google Play. See Cycella in Nepal and how it keeps your data private.