Due Date Calculator

Use this due date calculator to find your baby's estimated due date from your last period, conception date or IVF transfer date.

What Is a Due Date Calculator?

A due date calculator estimates the day your baby is expected to be born. Choose how you want to calculate it, enter the date and get your estimated due date plus key pregnancy milestones. Expecting parents in the United States use a due date calculator as soon as they get a positive test.

How to Calculate Your Due Date

• Last menstrual period (LMP): add 280 days, or use Naegele's rule of adding one year, subtracting three months and adding seven days. If your cycle is not 28 days, adjust by the difference.
• Conception date: add 266 days.
• IVF 5-day transfer: add 261 days. IVF 3-day transfer: add 263 days.

Key Dates in Your Pregnancy

Along with your due date, the calculator lists when your first trimester ends at 13 weeks, when your second trimester ends at 27 weeks and when full term begins at 37 weeks. Early term is 37 to 38 weeks, full term is 39 to 40 weeks and a baby is late term at 41 weeks.

How Accurate Is My Due Date?

A due date is a guide, not a deadline. Only about 4 to 5 percent of babies arrive on that exact day. First-time pregnancies, cycle length and ovulation timing all affect it. Providers often use a first-trimester ultrasound to confirm or correct the date, which is generally the most accurate dating method.

What Happens If I Go Past My Due Date?

Many healthy pregnancies run a week or two past the date. Your provider will monitor you and the baby and discuss options if labor has not started.

Planning Around Your Due Date

Use your due date to plan prenatal visits, maternity leave, childbirth classes and the nursery. Many parents also pack a hospital bag by 36 weeks since babies can arrive early.

Frequently Asked Questions

How do I calculate my due date from conception?

Select Conception date, enter it and the calculator adds 266 days.

What if I do not know my last period date?

Your provider can estimate your due date with an ultrasound.

Can my due date change?

Yes. It is often adjusted after an early ultrasound.

Estimates only. Your healthcare provider confirms your due date, often with an early ultrasound.