Calculate your likely ovulation date and fertile window for family planning.
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Enter Your Measurements
Results
Days Until Ovulation
-23
days
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Formula
Ovulation ≈ Day 14 of cycle (for 28-day cycles); varies by cycle length
How to Use This Calculator
How to Use
- 1
Enter your average cycle length.
- 2
Enter the first day of your last period.
- 3
Get your estimated ovulation date.
Frequently Asked Questions
Frequently Asked Questions
When does ovulation occur?
Ovulation typically occurs about 14 days before the next period. For a 28-day cycle, that's around day 14.
What is the fertile window?
The fertile window is about 5 days before ovulation through 1 day after. This is when pregnancy is most likely.
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About This Calculator
This calculator uses the formula: Ovulation ≈ Day 14 of cycle (for 28-day cycles); varies by cycle length. All calculations follow industry-standard methods. Results are estimates — always verify with a licensed professional for structural or code-compliant work.
Built and maintained by the CalcSmart team. Last updated March 2026.
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