Ovulation Calculator
Fertile window and ovulation day from your cycle.
Reviewed by the Calculation Machine team · How we check our maths
Your values
ⓘ Live results
Results
- Ovulation day of cycle
- Day 14
- Fertile window
- Day 9 to day 14
- Today's status
- Lower chance
- Days until ovulation
- 6 days
Quick answer
Ovulation happens about 14 days before the next period, and the fertile window is the five days before ovulation plus the day itself.
Worked example
Worked example
Using the values the calculator loads with.
Inputs
- Cycle length28 days
- Luteal phase length14 days
- Current day of cycle8
Result
- Ovulation day of cycleDay 14
- Fertile windowDay 9 to day 14
- Today's statusLower chance
- Days until ovulation6 days
How to use the Ovulation Calculator
- 1Enter your typical cycle length.
- 2Enter your luteal phase (usually 12–16 days).
- 3Enter today's cycle day to see your status.
Frequently asked questions
How long does the egg survive?
About 12–24 hours, but sperm can live up to five days, which is why the fertile window starts before ovulation.
Are these predictions reliable?
They are estimates. Ovulation predictor kits and basal body temperature tracking confirm the actual day.
About this calculator
- Built and reviewed by the Calculation Machine team · How we build and test calculators
- Report an error