Estimate your due date using the standard method doctors commonly start with — counting 280 days (40 weeks) from the first day of your last menstrual period. Your care provider may adjust this after an ultrasound, which is often more precise.
Pregnancy Due Date Calculator
LiveThe formula
A last menstrual period starting January 5, 2026: due date = January 5 + 280 days ≈ October 12, 2026.
Step-by-step guide
- Choose whether you know your last period date or your conception date.
- Enter the date and, if using your last period, your average cycle length (28 days is typical, but many people vary).
- Read your estimated due date, current week, and trimester.
Common mistakes
Frequently asked questions
How accurate is this estimate?
It's a widely used starting estimate, but an early ultrasound (typically in the first trimester) is generally considered more accurate, since it directly measures the size of the developing embryo or fetus rather than relying on cycle assumptions.
What if I don't know my last period date?
If you know your conception date instead, use that mode — it skips the cycle-length assumption entirely. Otherwise, a healthcare provider can date the pregnancy from an ultrasound.
Is it normal to deliver before or after the due date?
Yes — full-term delivery covers a range of about three weeks (roughly 37 to 42 weeks), so the due date is a single estimate within a normal range, not a precise deadline.
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