Menstrual Cycle Calendar Estimate Calculator
Explore dates under a regular-cycle assumption.
Your result
FITNESS & HEALTHEnter your values and select calculate.
On this page How it works & practical examples
How to use the Menstrual Cycle Calendar Estimate Calculator
Explore dates under a regular-cycle assumption. The possible fertility window row spans five days before through one day after the estimated ovulation date; actual ovulation is not measured.
The calculation
Worked example
A January 1 start, 28-day cycle and 14-day luteal assumption give an expected January 29 next period and approximate January 15 ovulation.
Assumptions and limits
Not a contraception method, confirmation of ovulation, conception or pregnancy. Cycle variability and individual physiology can shift dates materially; the interval is a supplied assumption.
Common questions
Which inputs should I use?
Explore dates under a regular-cycle assumption. The possible fertility window row spans five days before through one day after the estimated ovulation date; actual ovulation is not measured.
What does the result exclude?
Not a contraception method, confirmation of ovulation, conception or pregnancy. Cycle variability and individual physiology can shift dates materially; the interval is a supplied assumption.