Next Period Calculator
Estimate when the next six periods are likely to start.
Share sends a link that reopens these numbers. Copy details pastes the full breakdown as a list.
The formula
next period = first day of the last period + cycle length
Each date after that adds one more cycle length, so any difference between the average and a real cycle builds up the further ahead you look.
What to watch out for
Count from the first day of one period to the first day of the next, and use the average of a few cycles if you can. Unusual bleeding, severe pain or periods stopping unexpectedly are worth raising with a doctor or midwife.
Frequently Asked Questions
How do I work out my next period?
Add the cycle length to the first day of the last period. From 1 January 2027 with a 28-day cycle, that is 29 January 2027, then 26 February 2027.
What if cycles are irregular?
These dates become unreliable, especially the later ones, because each adds one more cycle of variation.
Can these dates be used as contraception?
These dates are only an estimate and are not reliable as contraception, because cycles vary and sperm can survive for several days.