Fitness & Health

Pregnancy Conception Calculator

Estimate conception date and likely fertile window from an expected due date.

Inputs

Defaults are prefilled so the result is visible immediately.

Estimated due date

Results

Results update as the calculator inputs change.

Estimated conception date

Feb 13, 2026

This is an estimate only and is not medical advice.

Likely fertile window start

Feb 8, 2026

Likely fertile window end

Feb 14, 2026

Estimated LMP

Jan 30, 2026

Due date

Nov 6, 2026

Formula and Assumptions

Estimated conception date = due date - 266 days; fertile window is shown around that estimate.

The conception estimate uses the common 266-day gestational age relationship.

The window is approximate because ovulation and implantation timing vary.

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 Conception Calculator.

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

Default inputs: dueDate=2026-11-06