Enter the first day of your last period — or a known conception date — and get an estimated due date, today's gestational age, trimester and days remaining.
All math runs locally in your browser. The dates you enter never leave your device.
For general information — not medical advice. Confirm dates with a healthcare provider.
The estimate is pure calendar arithmetic on UTC day counts, so time zones and daylight saving never skew it. Pick the dating anchor you actually know — the first day of your last period, or the conception date — and the calculator applies the standard clinical rules.
Because gestational age is counted from the first day of your last period, not from conception. Ovulation usually happens about 14 days into the cycle, so by the time the egg is fertilised you are already about two weeks 'pregnant' in gestational terms. 40 weeks from LMP ≈ 38 weeks from conception — both describe the same pregnancy, just from different starting lines.
As a single date, not very — only about 1 in 20 babies arrive on their exact due date, and most arrive within the 37–42 week term window. As a window it is reliable: an LMP-based estimate is typically within one to two weeks, and an early ultrasound (often around 8–13 weeks) refines it further by measuring the baby.
It gives a reasonable estimate, but the maths assumes a regular cycle. If your cycles average more or less than 28 days, use the cycle-length slider, or the conception mode if you know the date. With genuinely irregular cycles, an early ultrasound is the most reliable way to date a pregnancy — ask your provider.
No. This is arithmetic based on standard dating rules (Naegele's rule and its cycle-length adjustment), nothing more. Treat the output as an estimate and confirm it with a healthcare provider — especially after IVF or fertility medication, where your clinic uses its own dating based on the exact transfer and embryo age. If anything feels wrong, contact your provider, not this page.
No — and that matters here, so it is worth stating clearly: the calculation runs entirely in your browser. The dates you enter are never transmitted, stored or logged anywhere; they exist only on your device while you use the page and disappear when you close it.
If you just finished with Pregnancy Due Date Calculator, the natural next steps are Weight Gain in Pregnancy, Age Calculator, Calorie Calculator, or browse every tool in Health Tools.