Estimated due date
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Enter a date to begin
Due date calculator by LMP
Enter the first day of your last menstrual period—this page opens on the LMP tab with an example date you can replace with yours.
Your dates
Choose a method. Results update as you type.
Educational only — not medical advice
We add 280 days (40 weeks) from this date — the classic pregnancy wheel.
BMI for weight-gain guide
Your snapshot
Current pregnancy
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Trimester —
Countdown
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Estimated conception (LMP + 14 days): —
Baby size this week
Enter your LMP (or other method) to see a playful size comparison.
How your due date is calculated
Most clinics estimate due date using Naegele’s rule: start from the first day of your last menstrual period (LMP) and add 280 days (40 weeks). This assumes a 28-day cycle with ovulation around day 14, which is not true for everyone — dating ultrasounds in the first trimester can refine timing.
What is LMP?
LMP means the first day of bleeding from your last period before this pregnancy — not spotting, and not the last day. If your cycles are longer or shorter than 28 days, your clinician may adjust the estimated due date.
Pregnancy stages (trimesters)
- First trimester: weeks 1–13 — organ formation, often fatigue and nausea.
- Second trimester: weeks 14–27 — many feel more energetic; anatomy scan window.
- Third trimester: weeks 28–40+ — rapid fetal growth, Braxton Hicks, birth planning.
How accurate is a due date?
Only about 5% of babies arrive on the “due date.” A term window of roughly 37–41 weeks is common. Ultrasound dating in early pregnancy reduces error compared to LMP alone, especially if cycles are irregular.