Fitness & Health

Pregnancy Calculator

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

Inputs

Defaults are prefilled so the result is visible immediately.

First day of last period

Average cycle lengthdays

Results

Results update as the calculator inputs change.

Estimated due date

Nov 6, 2026

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

Formula and Assumptions

Estimated due date = LMP + 280 days + cycle-length adjustment.

Cycle length adjusts ovulation from the standard 28-day-cycle assumption.

Clinical dating can change after ultrasound or provider review.

Reference Upgrade

Built from the Calculator.net model, with added context.

Live validation and instant result updates instead of a submit-only workflow.

Multiple decision metrics are shown together, not only the primary answer.

Formula notes and assumptions are visible on the page so the math is easier to audit.

Reference Model

Modeled after the input style and primary output on Calculator.net's Pregnancy Calculator.

The page keeps the math in one place and exposes the assumptions beside the result.

Default inputs: lastPeriod=2026-01-30, cycleLength=28