Estimated due date
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Enter a date to begin
Pregnancy week calculator
Find your current pregnancy week and trimester. We pre-fill an example LMP around 18 weeks—swap in your real dates for instant results.
Your dates
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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.