Free Conception Calculator - When Did You Conceive?
Calculate your estimated conception date based on due date or last menstrual period. Understand pregnancy dating.
Quick Answer
Conception typically occurs about 2 weeks after the first day of your last period (around ovulation). From due date, conception = due date minus 266 days. From LMP, conception ≈ LMP + 14 days.
Key Facts about Conception Calculator:
- Conception usually 14 days after LMP
- Pregnancy dated from LMP, not conception
- Due date is 280 days (40 weeks) from LMP
- Conception = due date - 266 days
- Sperm can survive 5 days
- Exact conception day often uncertain
Why Use Our Conception Calculator?
Conception dating:
Date Calculator
Estimate conception date.
Multiple Methods
From due date or LMP.
Fertile Window
Show possible conception range.
Pregnancy Timeline
Key dates and milestones.
Instant Results
Get estimate immediately.
Private
Your data stays secure.
How to Conception Calculator in 3 Easy Steps
Calculate conception:
Choose Method
Due date or last period.
Enter Date
Your known date.
View Estimate
See conception date range.
Why Use Our Calculator?
Multiple calculation methods
Date range provided
Understand pregnancy dating
Timeline overview
Common Use Cases for Conception Calculator
Perfect for:
Frequently Asked Questions
Everything you need to know about our conception calculator
How accurate is conception date?
Estimate within ~5 days - exact day rarely known.
Conception date is an estimate with ~5 day range. Exact day is rarely known since sperm survive up to 5 days and ovulation day varies.
Why is pregnancy 40 weeks but conception is 38?
Dated from LMP (2 weeks before conception). 40 weeks from LMP = 38 from conception.
Pregnancy is dated from last menstrual period (LMP), which is about 2 weeks before conception. So 40 weeks from LMP = 38 weeks from conception.
Still have questions? Try the tool yourself!
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