Due Date Calculator
Estimate a pregnancy due date from last period, ultrasound dating, conception date, or IVF embryo transfer.
Estimate due date
Estimated due date
147 days from today · gest. 19w 0d
Implied LMP
Mon, Jun 15, 2026
Implied conception
Mon, Jun 29, 2026
About 40 weeks from LMP is the usual reference. Most births fall somewhere in the 37–42 week band; landing on the exact day is uncommon. Preterm range if birth now.
Estimate only — not medical adviceView details
These dates are calendar estimates from average cycle and pregnancy lengths. They are not a diagnosis, not contraception, and not a substitute for clinical care. Talk with a qualified clinician about your situation.
How it works
A due date is an estimate of when pregnancy reaches about 40 weeks of gestational age—not a promise that labor starts that day. Most births occur in a window around the estimate.
The most common dating method counts about 280 days from the first day of the last menstrual period (LMP). Conception-based dating often uses about 266 days from fertilization.
Ultrasound measurements early in pregnancy can refine dating when LMP is uncertain. IVF transfers use embryo age plus transfer date for a more specific estimate.
Enter the dating method you know best. If methods disagree, clinicians usually follow a consistent rule based on how far along you are and measurement quality—this tool cannot replace that judgment.
Use the Pregnancy Calculator for trimester timelines and milestones once you have a reference date. Always confirm prenatal scheduling with your care team.
Frequently asked questions
- Will my baby arrive on the due date?
- Usually not. Most births fall within a multi-week window around the estimate. The date is a clinical reference, not a guarantee.
- Which dating method is most accurate?
- It depends on data quality. Early ultrasound and IVF dating are often preferred when LMP is unknown or cycles are irregular, but your clinician decides what to chart.
- What if my cycles are longer than 28 days?
- LMP dating assumes a typical cycle pattern. Longer or irregular cycles can shift ovulation, so ultrasound dating is frequently more reliable in those cases.
- Is this medical advice?
- No. It is an educational estimator. Prenatal care decisions belong with a qualified clinician.
Related calculators
- Pregnancy CalculatorTrack gestational age, trimester, and milestone dates from LMP, due date, ultrasound, conception, or IVF.
- Ovulation CalculatorProject ovulation days and fertile windows for upcoming cycles from your last period and cycle length.
- Period CalculatorForecast upcoming period and ovulation dates using your last period start, cycle length, and bleeding days.
- Conception CalculatorHighlight peak fertile days across cycles and show the estimated due date if conception happens that month.