# Due Date Calculator

> Due date calculator: estimate your pregnancy due date from the first day of your last period or your conception date. Free, private, runs in your browser.

- **Canonical URL:** https://boringtoolskit.com/due-date-calculator/
- **Category:** Everyday Calculators
- **Evidence level:** authored-methodology
- **Reviewed:** August 2026
- **Last verified:** 2026-10-12
- **Privacy:** Inputs and results stay in this browser unless the page clearly labels an external request.

## How it works

Due date = LMP + 280 days (40 weeks) or conception + 266 days.

## Sources

- [Calculation methodology and verification standard](/methodology/)

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*Local planning estimate. Verify current terms, rates, and policies before acting.*