Health

Pregnancy Due Date Calculator

Free pregnancy due date calculator — estimate your baby's due date, current pregnancy week, trimester, and key milestones from your last menstrual period (LMP) or conception date.

Short answer: Pregnancy Due Date Calculator — Find your baby's due date and pregnancy week. Free pregnancy due date calculator — estimate your baby's due date, current pregnancy week, trimester, and key milestones from your last menstrual period (LMP) or conception date. It answers “pregnancy due date calculator by last period”. Who it is for: Expectant parents finding an estimated due date; Anyone working out how many weeks pregnant they are; People planning appointments by trimester. It runs entirely in your browser — no sign-up, no account, no email and no upload — and every result can be exported as a dated PDF report.

✔ Price: free, unlimited use, no rate limits
✔ Sign-up: not required
✔ Privacy: all math runs client-side, nothing is uploaded
✔ Export: one-click PDF report (2026 rates)

Calculate by

First day of LMP

Cycle length (days)

Estimated due date

Thu, Aug 19, 2027

Currently

0w 0d

Trimester

Days to go

279

Estimate only — confirm with your healthcare provider. Ultrasound dating is more accurate.

Popular long-tail searches from Canada and Australia — jump straight to the tool.

Long-tail searches trending across the UK, New Zealand & Ireland — click to open the matching tool.

→ Browse all free tools → Explore by category → Read the blog

Who is this tool for?

✔ Expectant parents finding an estimated due date
✔ Anyone working out how many weeks pregnant they are
✔ People planning appointments by trimester
✔ IVF patients checking a transfer-based due date
✔ Partners planning leave around a due date

How to use Pregnancy Due Date Calculator

Enter the first day of your last menstrual period (LMP).
Adjust cycle length if not 28 days.
See your estimated due date (EDD), current week, and trimester.

Frequently asked questions

How is pregnancy due date calculated?

By Naegele's rule: add 280 days (40 weeks) to the first day of your last menstrual period. This calculator adjusts for cycles longer or shorter than 28 days.

How many weeks is a full pregnancy?

40 weeks from LMP, or 38 weeks from conception. Full-term is 37–42 weeks.

What trimester am I in?

First trimester: weeks 1–12. Second: weeks 13–27. Third: weeks 28–40+.

How accurate is the due date?

Only about 5% of babies arrive on the exact due date. Most arrive within 2 weeks before or after. An early ultrasound is the most accurate dating method.

Can I use this if I don't know my LMP?

Yes — switch to the conception date option and enter your estimated date of conception.

Is this calculator a substitute for a doctor?

No. Always confirm your due date with a healthcare provider — they will use ultrasound measurements for the most accurate estimate.

Pregnancy due date calculator by last period?

Use the Pregnancy Due Date Calculator above: Find your baby's due date and pregnancy week. Free pregnancy due date calculator — estimate your baby's due date, current pregnancy week, trimester, and key milestones from your last menstrual period (LMP) or conception date.