Project the next period using cycle lengths you enter.
Starting values are an example. Replace them with your own.
Your inputs stay in your browser.
Enter your details and run the calculation.
The range is based on your inputs, not a clinical prediction. It does not establish pregnancy, fertility or a health condition. Discuss changes in your cycle with a healthcare professional.
Full disclaimerThe calculator adds your typical cycle length to the first day of your last period to give the expected start of the next one. The earlier and later dates come from the shortest and longest cycles you have recorded, and cycles from 15 to 90 days are supported. Cycles can change, so the range depends only on your inputs and is not a clinical forecast. It does not confirm pregnancy or fertility, so discuss changes in your cycle with a gynaecologist.
Add your cycle length to the first day of your last period. If it started on 1 October 2026 and your cycle is 28 days, the next is expected on 29 October. With a shortest cycle of 26 days and a longest of 31, the range is 27 October to 1 November.
No. A period calendar only projects dates from the cycle lengths you enter and does not confirm pregnancy, fertility or any health condition. If your period is late or your cycle changes noticeably, take a test or see a gynaecologist for personal advice.
METHOD
Next start = entered date + entered cycle length.
TRACEABLE