Ori ToolsHow to use
- Enter the first day of your last period.
- Enter your usual cycle length.
- Press Calculate.
When to use it
- Getting a rough idea of your cycle
- Planning around expected dates
- Learning how cycle length shifts ovulation
Calendar method
Ovulation usually happens about 14 days before the next period, not 14 days after the last one. With a 32-day cycle, that is around day 18. Cycles vary, so this estimate can be off by several days.
Frequently asked questions
Can I use this as birth control?
No. Calendar estimates are not reliable enough.
What if my cycle is irregular?
The estimate will be less accurate; ovulation tests or a doctor can help.
Is my data stored?
No, the dates stay in your browser.