Pregnancy Due Date Calculator - Estimate Due Date Online Free

How to Use the Due Date Calculator

1. Choose your calculation method — select “Last Menstrual Period (LMP)” or “Conception Date”
2. Enter the date — pick your LMP date or the date of conception using the date picker
3. View your estimated due date — the calculator displays the estimated due date immediately
4. Check current pregnancy week — if you enter a past LMP date, see how many weeks along and which trimester you’re in
5. Review milestones — key milestones like end of first trimester and viability are calculated automatically

Calculate your estimated due date and track your pregnancy progress week by week. All calculations stay in your browser.

Features

• LMP method — standard 280-day (40-week) calculation based on last menstrual period
• Conception date method — use this if you know the exact date of conception (typically 266 days from conception to due date)
• Current pregnancy week — see exactly how far along you are based on today’s date
• Trimester indicator — shows current trimester (1st: weeks 1-13, 2nd: weeks 14-27, 3rd: weeks 28-40)
• Key milestones — quick reference for important pregnancy milestones
• Simple interface — one screen with all results visible after date entry

Use Cases

• Pregnancy tracking — get your estimated due date right after a positive pregnancy test
• Appointment planning — know your trimester dates to schedule prenatal appointments and screenings
• Maternity leave planning — use the due date to plan your maternity or paternity leave start date
• Sharing the news — tell family and friends your expected due date with confidence
• Weekly progress — check back each week to see your current week and upcoming milestones

FAQ

How accurate is the due date estimate?

Only about 4% of babies are born on their exact due date. The due date is an estimate — full-term pregnancy ranges from 37 to 42 weeks. The calculator gives a statistically reasonable estimate based on standard medical formulas.

What’s the difference between LMP and conception date methods?

The LMP method adds 280 days (40 weeks) from the first day of your last period. The conception date method adds 266 days (38 weeks) from the date of conception. For most women with regular 28-day cycles, both methods give similar results.

Can I calculate based on IVF transfer date?

This calculator uses LMP and conception methods. If you had an IVF transfer, your fertility clinic will provide a due date based on the transfer date and embryo age (day 3 or day 5). Consult your clinic for the most accurate calculation.

What if my cycle is not 28 days?

The standard 280-day calculation assumes a 28-day cycle. For longer or shorter cycles, the due date may shift. Talk to your healthcare provider about adjusting your due date based on your cycle length or early ultrasound measurements.

Does this replace a doctor’s confirmation?

No — this is an informational tool only. Always confirm your due date with a healthcare provider through ultrasound and clinical evaluation. Early ultrasound dating in the first trimester is the most accurate method.