👶 Due Date Calculator

First Day of Last Period

Cycle Length (days)

Conception Date (Estimated)

What is the Due Date Calculator?

The Due Date Calculator estimates when your baby is likely to arrive. Enter the first day of your last menstrual period (LMP) and your typical cycle length, or enter an estimated conception date, and it returns your estimated due date, current week of pregnancy, trimester, days remaining, and an estimated conception date.

How to Use It

Choose the "Last Period" tab and enter the first day of your LMP plus your cycle length (default 28 days), then press Calculate. If you know your conception date instead, switch to the "Conception Date" tab and enter it directly. The tool adjusts automatically for cycles longer or shorter than 28 days.

When to Use It

Use it as soon as you know you're pregnant to get a rough delivery timeline, before your first prenatal appointment, or any time during pregnancy to check which week and trimester you're in and how many days remain. It's also handy for planning maternity leave, baby showers, and hospital bags around a target date.

Who Benefits

Expecting parents, partners, and family members tracking a pregnancy will find it useful for quick estimates between doctor visits. It's a planning aid, not a medical diagnosis — an ultrasound dating scan from your OB-GYN or midwife remains the most reliable way to confirm your due date, since only about 5% of babies arrive on their exact calculated day.

Frequently Asked Questions

The most common method is Naegele's Rule: add 280 days (40 weeks) to the first day of your last menstrual period (LMP). Alternatively, add 9 months and 7 days to the LMP date. This assumes a 28-day cycle with ovulation on day 14.

Only about 5% of babies are born on their exact due date. Most births occur within 2 weeks before or after the due date. A due date is best understood as the midpoint of a normal delivery window — roughly 38–42 weeks gestation.

If your cycle is longer than 28 days, your due date will be later; if shorter, earlier. For example, with a 35-day cycle, ovulation occurs around day 21, adding 7 days to the standard calculation. Your OB will typically use an early ultrasound to confirm the due date.

👶 Due Date Calculator