Conception Calculator
Estimate the date of conception from your last period date or expected due date. Find your fertile window.
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How to Use the Conception Calculator
- Enter your last menstrual period date, or enter your expected due date instead.
- Click Calculate to estimate your conception date and fertile window.
- Review the estimated conception date and the range of likely fertile days.
- Use the results to plan or understand your pregnancy timeline.
Quick Reference
| From | To |
|---|---|
| 1st trimester | Weeks 1–12 |
| 2nd trimester | Weeks 13–26 |
| 3rd trimester | Weeks 27–40 |
| Due date | 40 weeks (280 days) |
| Full term | 37–42 weeks |
| Preterm | < 37 weeks |
Use Cases
- •Monitoring personal health metrics as part of a wellness routine.
- •Setting evidence-based goals for diet, exercise, or weight management.
- •Preparing for a medical appointment with baseline body measurements.
- •Tracking changes in body composition over time.
Formula
Conception ≈ last period + 14 days, or due date − 266 days. Fertile window: conception ± 3 days.
Frequently Asked Questions
How to use?
Enter your last period date or due date, then click Calculate to see your estimated conception date and fertile window.
Calculation accuracy?
Calculations are performed with high precision.
Is it free?
Yes, all calculators are completely free.