Fitness & Health

Pregnancy Calculator

Estimate due date, conception date, and trimester milestones from last menstrual period.

Inputs

Results update as you edit.

First day of last period

Average cycle length

days

Estimated due date

Nov 6, 2026

Results update as the calculator inputs change.

This is an estimate only and is not medical advice.

Estimated conception

Feb 13, 2026

Second trimester begins

May 8, 2026

Third trimester begins

Aug 7, 2026

40-week date

Nov 6, 2026

How to Estimate Pregnancy Dates

Last Menstrual Period

A common estimate starts from the first day of the last menstrual period.

280-Day Estimate

A typical due-date estimate adds about 280 days, adjusted for cycle length when used.

Milestones

Trimester and conception estimates are planning dates, not exact clinical determinations.

How to Use Pregnancy Date Estimates

Pregnancy calculators provide estimated dates from common dating rules. Clinical dating can change after ultrasound or provider review, especially when cycle timing is uncertain.

What Affects Pregnancy Dating?

LMP Date

The first day of the last period is the starting point for many estimates.

Cycle Length

Longer or shorter cycles can shift estimated ovulation and due date.

Ovulation Timing

Ovulation does not always occur on day 14.

Ultrasound Dating

Early ultrasound can refine dating in clinical care.

Provider Review

Your provider may update the official due date based on medical guidance.

Estimate Limits

Only a small share of births occur exactly on the due date.

Pregnancy Date References

Due Date

Estimate the expected due date from LMP and cycle length.

Conception Window

Estimate likely conception timing from the due-date model.

Trimester Milestones

Preview approximate trimester transition dates.

Frequently Asked Questions

Is the due date exact?

No. It is an estimate. Your clinician may adjust it using ultrasound and medical history.

Why use the first day of the last period?

Pregnancy dating often starts from LMP because it is usually easier to identify than ovulation or conception.

Does cycle length matter?

Yes. Longer or shorter cycles can shift estimated ovulation and due date.

Can this confirm pregnancy?

No. It only estimates dates. Use a pregnancy test and medical care for confirmation.

Should I use my provider's due date?

Yes. Use the due date documented by your clinician for medical decisions.