Estimate when your baby is due. This free due date calculator works from your last period, conception date or IVF transfer, shows how far along you are today, and gives the estimated conception date.
This tool gives an estimated due date for general information. Only about 1 in 20 babies arrives on the exact due date — most arrive in the two weeks around it. Always confirm with your midwife or doctor, whose dating scan is more accurate.
Estimate from
days
Based on a typical 40-week (280-day) pregnancy from the last period. If your cycle isn’t 28 days, the estimate is adjusted accordingly.
Estimated due date
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Enter a date
How far along today
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Trimester (today)
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Estimated conception
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Days until due date
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Estimates only and not medical advice. A dating ultrasound and your healthcare provider give the most accurate due date, especially with irregular cycles.
Use this free due date calculator to estimate when your baby is due. Work it out from your last period, conception date or IVF transfer, and see how far along you are today.
What this due date calculator does
A due date calculator estimates your estimated due date (EDD) — roughly 40 weeks from the first day of your last period. You can also estimate from a known conception date or an IVF embryo transfer.
How the due date is calculated
From last period: due date = first day of last period + 280 days
From conception: due date = conception date + 266 days
This follows Naegele’s rule. For a last period starting 1 January, the estimated due date is about 8 October. If your cycle isn’t 28 days, the calculator adjusts the estimate.
Pregnancy by trimester
Trimester
Weeks
First
1 – 13
Second
14 – 27
Third
28 – 40+
How accurate is a due date?
It’s an estimate. Only about 1 in 20 babies arrives on the exact date, and a normal, full-term birth can happen anytime from 37 to 42 weeks. An early dating ultrasound is the most accurate way to confirm it, especially with irregular cycles.
How to use the due date calculator
Choose your starting point — last period, conception or IVF.
Enter the date (and cycle length if you know it).
Read your estimated due date and how far along you are.
Due Date FAQ
How is a due date calculated?
Most due dates use Naegele's rule: add 280 days (40 weeks) to the first day of your last period. From a conception date, add 266 days. The calculator does both.
How accurate is a due date?
It's an estimate — only about 1 in 20 babies arrives on the exact date. A full-term birth normally happens between 37 and 42 weeks, and a dating scan is the most accurate confirmation.
Can I calculate a due date from conception or IVF?
Yes. Switch modes to use a known conception date (+266 days) or an IVF transfer, choosing a day-3 or day-5 embryo, and the calculator adjusts accordingly.
What if my cycle isn't 28 days?
Enter your average cycle length and the estimate is shifted by the difference, since ovulation — and so conception — happens earlier or later than the standard assumption.
How many weeks is a full-term pregnancy?
About 40 weeks from the last period, grouped into three trimesters. Babies born from 37 weeks are considered full term.
Is the due date calculator free?
Yes, this due date calculator is completely free, needs no sign-up, and gives instant results in your browser.
