🤰 Pregnancy Due Date Calculator
Estimate your baby's due date and see how far along you are, using Naegele's Rule.
Estimated Due Date
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Trimester
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Weeks Pregnant
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Days Left
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How the Due Date Is Calculated
Naegele's Rule estimates a due date as 280 days (40 weeks) from the first day of your last menstrual period. If you know your conception date instead, we add 266 days (38 weeks), since conception typically occurs about two weeks after the last period.
Only about 1 in 20 babies arrive exactly on their due date — think of it as a target window rather than a fixed deadline. A doctor's ultrasound dating is more precise than either method here.
Who Uses This Tool?
- Expecting parents planning around a due date estimate
- Anyone tracking which trimester they're currently in
- People preparing questions ahead of a prenatal appointment
- Family and friends planning a baby shower timeline
It's a standard estimate based on Naegele's Rule, the same method used by most online pregnancy calculators. Actual delivery dates commonly fall anywhere within about two weeks of the estimate.
Naegele's Rule assumes a 28-day cycle. If yours is longer or shorter, your doctor may adjust the estimate — an early ultrasound is the most reliable way to confirm dating.
First trimester is weeks 1 to 13, second trimester is weeks 14 to 27, and third trimester runs from week 28 until birth, typically around week 40.
No. All calculations happen instantly in your browser — nothing you enter is stored or shared.