Pregnancy Due Date Calculator

Report an Issue

Help us improve by telling us what went wrong.

Embed this Tool

Customize and copy the embed code for your website.

Find Out When Your Baby Is Due

Pregnancy brings excitement, planning, and one question that comes up almost immediately: when is the baby due? The Pregnancy Due Date Calculator estimates your expected delivery date based on the first day of your last menstrual period or your conception date. It is the same calculation your doctor performs at your first prenatal visit, available here instantly and privately.

How the Calculation Works

The standard method, known as Naegele's rule, takes the first day of your last menstrual period, adds seven days, and then adds nine months (or equivalently, adds 280 days). This assumes a 28-day menstrual cycle with ovulation occurring on day 14. If your cycle is longer or shorter than 28 days, the calculator can adjust accordingly for a more accurate estimate.

If you know your exact conception date - perhaps through fertility tracking or IVF - the calculator adds 266 days (38 weeks) from that date instead. Both methods arrive at an estimated due date that falls within the typical full-term pregnancy range.

What Your Due Date Actually Means

Here is something many first-time parents do not realise: only about 4% of babies arrive exactly on their due date. The estimated date is the midpoint of a window. Full-term delivery anywhere between 37 and 42 weeks is considered normal. So treat the date as a strong guideline, not a deadline.

That said, the due date is enormously useful for planning. It helps you and your healthcare provider schedule prenatal appointments, plan maternity or paternity leave, prepare the nursery, and monitor fetal development against expected milestones.

Who Uses This Calculator

Expectant mothers are the primary users, often checking within days of a positive pregnancy test. Knowing the approximate due date helps with everything from telling family to booking hospital tours.

Partners and family members use it to plan around the expected arrival - booking time off work, arranging travel, or coordinating support during the postpartum period.

Healthcare professionals sometimes use quick calculators like this as a reference check, especially in settings where a full dating ultrasound has not yet been performed.

Women tracking fertility use the calculator in conjunction with ovulation tracking to estimate how far along they are before their first prenatal appointment confirms the timeline.

Trimester Breakdown

Beyond the due date itself, the calculator can show which trimester you are currently in. The first trimester covers weeks 1 through 12, the second spans weeks 13 through 26, and the third runs from week 27 until delivery. Each trimester brings different developmental milestones and different preparation priorities, so knowing where you stand helps you focus your attention.

Important Considerations

Irregular menstrual cycles can shift the estimated due date. If your cycles are significantly longer or shorter than 28 days, mention this to your healthcare provider. An early ultrasound, typically performed between weeks 8 and 12, provides the most accurate dating and may adjust the estimate.

Multiple pregnancies (twins, triplets) often deliver earlier than the standard 40-week estimate. The calculator provides a singleton pregnancy estimate by default.

This tool is for informational purposes and does not replace professional medical advice. Always confirm your pregnancy due date with your doctor or midwife.

Private and Instant

The Pregnancy Due Date Calculator runs entirely in your browser. No personal health information is stored, transmitted, or logged. You get your result immediately, privately, and can return as often as you like to check your progress week by week.