Pregnancy Due Date Calculator — From LMP or Conception Date

Few dates feel as exciting to work out as a due date. This pregnancy calculator estimates it two ways. If you know the first day of your last menstrual period, it uses Naegele's rule — counting 280 days (40 weeks) forward — and adjusts for your cycle length so the estimate fits you rather than a textbook 28-day average. If instead you know your conception date, it counts 266 days from there.

Beyond the due date, the calculator tells you how far along you are right now: your current pregnancy week, which trimester that falls in, and how many days remain until your estimated due date. It also lays out the key milestone dates ahead — the end of the first trimester, the anatomy scan around weeks 18 to 20, the viability point at 24 weeks, full term at 37 weeks, and the 40-week due date itself — so you can see the journey mapped out.

It's important to treat the result as an estimate. Only about one baby in twenty arrives on the exact due date; most come within a fortnight either side, and a pregnancy is considered full term any time from 37 weeks. Your healthcare provider will confirm and may revise your due date based on an early ultrasound, which measures the baby directly and is generally the most accurate dating method.

This tool is for general information and planning, not medical care — always follow your midwife or doctor's guidance throughout your pregnancy. Everything is calculated privately in your browser, so your dates stay completely confidential. Enter your details above, and use the ovulation calculator if you're planning, or the countdown timer to count down to the big day.