When is my next period

Start with the first day of the last period

Most people estimate the next period by taking the first day of the last period and adding their usual cycle length. If your cycle is usually 28 days and your last period started on April 1, the next period is expected around April 29.

This estimate works best when your cycle is fairly steady. It gives you a planning anchor for travel, appointments, and symptom tracking.

Use cycle length, not bleeding length

The cycle length is the number of days from one period start date to the next. It is different from period length, which only counts the bleeding days.

• Count from the first day of bleeding, not the last day.
• Use the cycle length that feels most common in the last few months.
• Expect some movement if life has been busy or your body feels different this month.

Use a calculator when you want the full monthly picture

If you want a faster answer, a period calculator can estimate the next period, ovulation day, and fertile window together. That fuller view is easier to use than doing the math by hand every month.

If your cycle changes a lot from month to month, a range-based calculator for irregular periods is the better fit.