Is this due date calculator free?

Yes, completely free — no account, no subscription, no hidden fees. Open the page and get your due date instantly.

How is the due date calculated?

The calculator uses Naegele's rule: take the first day of your last menstrual period, subtract 3 months, add 7 days, then adjust for cycles other than 28 days. This gives an estimated due date approximately 40 weeks from the LMP.

How accurate is the estimated due date?

Naegele's rule gives a statistical estimate — only about 5% of babies arrive on the exact due date. Most births occur within 2 weeks before or after the EDD. An ultrasound scan in the first trimester provides a more precise date.

What if my cycle is irregular or not 28 days?

Adjust the cycle length slider to your average cycle. The tool shifts the due date accordingly — longer cycles (e.g. 35 days) push it later; shorter cycles (e.g. 21 days) pull it earlier. For very irregular cycles, consult your doctor or use an early ultrasound for dating.

Is my pregnancy data private?

Yes. All calculations run entirely in your browser. Your last menstrual period date and cycle length are never sent to any server, never stored in the cloud, and never shared with anyone. Your data stays on your device only.

🤰 Pregnancy Due Date Calculator — Free & Private

Enter your last menstrual period (LMP) date and your average cycle length to instantly see your estimated due date and how many weeks pregnant you are today — all calculated in your browser with no data ever sent to a server.

First day of your last period

Cycle length (days)

Estimated due date

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Private by design. This tool runs entirely in your browser — nothing you enter is uploaded or stored, and it works offline.

About

This due date calculator uses Naegele's rule, the standard method used by midwives and obstetricians worldwide: take the first day of your last menstrual period, subtract 3 months, add 7 days, then adjust for your cycle length (longer cycles shift the due date later; shorter cycles shift it earlier). The result is your estimated due date (EDD) — typically around 40 weeks from the LMP. The tool also calculates your current pregnancy week and day so you always know exactly where you are in your pregnancy. Because everything runs client-side in your browser, your dates are never uploaded, stored on a server, or shared with anyone — your pregnancy data stays completely private.

How to use

Enter the first day of your last menstrual period (LMP) in the date field.
Set your average cycle length (default is 28 days; adjust if yours differs).
Your estimated due date (EDD) is calculated instantly using Naegele's rule.
See your current pregnancy week and day — updated automatically based on today's date.

FAQ

Is this due date calculator free?: Yes, completely free — no account, no subscription, no hidden fees. Open the page and get your due date instantly.
How is the due date calculated?: The calculator uses Naegele's rule: take the first day of your last menstrual period, subtract 3 months, add 7 days, then adjust for cycles other than 28 days. This gives an estimated due date approximately 40 weeks from the LMP.
How accurate is the estimated due date?: Naegele's rule gives a statistical estimate — only about 5% of babies arrive on the exact due date. Most births occur within 2 weeks before or after the EDD. An ultrasound scan in the first trimester provides a more precise date.
What if my cycle is irregular or not 28 days?: Adjust the cycle length slider to your average cycle. The tool shifts the due date accordingly — longer cycles (e.g. 35 days) push it later; shorter cycles (e.g. 21 days) pull it earlier. For very irregular cycles, consult your doctor or use an early ultrasound for dating.
Is my pregnancy data private?: Yes. All calculations run entirely in your browser. Your last menstrual period date and cycle length are never sent to any server, never stored in the cloud, and never shared with anyone. Your data stays on your device only.