Health
Calculator for Pregnancy Due Date
Estimate due date from the first day of the last menstrual period with Naegele's rule (280 days).
Add to workspaceYour numbers
Result dey update as you type; no Calculate button dey. All calculation dey run inside your browser.
Estimated due date
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How your result break down
| Measure | Value wey e get |
|---|---|
| First day of your last period | — |
| Estimated due date (LMP + 280 days) | — |
| Approximate conception date | — |
| Gestational age for today | — |
| Trimester boundaries | — |
We dey calculate gestational age today from the LMP wey you enter to today's date, so e dey change every day. The due date itself no dey change once the LMP stay the same.
Formula
Estimated due date = first day of last menstrual period + 280 days (40 weeks). Na Naegele's rule be this. E assume regular 28-day cycle with ovulation on day 14, na why we show approximate conception date as LMP + 14 days. Trimester boundaries wey we show na LMP + 14 weeks and LMP + 28 weeks.
Example wey show the calculation
Last menstrual period 2026-01-01: estimated due date = 2026-01-01 + 280 days = 2026-10-08. Approximate conception date (if cycle na 28-day cycle) na 2026-01-15. On reference date 2026-09-10, gestational age na (2026-09-10 − 2026-01-01) = 252 days = 36 weeks 0 days, with 28 days (4 weeks 0 days) wey remain before the estimated due date. Use Reset example above to reproduce the due date; gestational age today on the live page dey use today's actual date.
Where e fit work and limits
Naegele's rule na estimate wey depend on two assumptions wey no always hold: regular 28-day cycle and ovulation on day 14. Longer or irregular cycles, LMP dates wey you no sure of and ultrasound dating fit all change the estimate. Actual delivery date dey vary from person to person — na only small part of births dey happen exactly on the estimated date. This page no replace prenatal care records or clinical dating, and e no make any claim about the health of any pregnancy.
Questions wey people dey ask often
Wetin Naegele's rule be?
Add 280 days (40 weeks) to the first day of the last menstrual period. Na common rough rule for dating pregnancy, no be measurement.
Why the real date fit differ?
Because cycles dey vary: ovulation no always happen on day 14, cycle lengths dey differ, and you fit no sure of the LMP date itself. Ultrasound dating often dey help refine the estimate.
Wetin if my cycles pass 28 days?
Then ovulation likely happen after day 14, and the true due date fit come after this estimate. This page no adjust for cycle length — make clinical dating handle that adjustment.
Due date mean say the baby must arrive that day?
No. Na estimate near the centre of a range; actual delivery dates fit differ well well around am.
Una dey store my data?
No. This calculation dey run locally inside your browser; values wey you enter no dey reach any CalcMintly database.
I suppose use this one make medical decisions?
No. Use prenatal care records and clinical advice for medical decisions; this page only dey show how Naegele's rule arithmetic work.
Other tools wey relate to dis
- Calculator for age — age from birth date
- Calculator for difference between dates — days between any two dates
- Calculator for BMI — body mass index from height and weight
Results na estimates only and no constitute professional or medical advice.