Pregnancy toolsFree and private
Due Date CalculatorFrom your last period, conception or IVF transfer
Find out when your baby is due, how many weeks along you are and the date of every scan that matters. It takes one date, works for IVF pregnancies to the day, and nothing you enter ever leaves your phone.
- 280 Days from your last period
- 3 Embryo ages day 3, 5 and 6 transfers
- 8 Milestones each with its own date
- 0 Dates stored it all stays on your phone
Calculator
When is your baby due?
Choose what you know, add the date, and the answer appears straight away.
Your timeline
Your pregnancy, date by date
Dated for the example above. Add your own date and every stop moves with it.
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Week 7 Early pregnancy scan Around 6 to 8 weeks: the first look at the heartbeat. After IVF your clinic usually books this one.You are here · 10w 0d 5 Oct 2026 3 weeks ago
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Week 12 Dating scan Between 11 and 14 weeks: confirms your due date and checks early development.You are here · 10w 0d 9 Nov 2026 in 2 weeks
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Week 14 Second trimester From 14 weeks many people feel more energy, and the risk of miscarriage falls.You are here · 10w 0d 23 Nov 2026 in 4 weeks
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Week 20 Anatomy scan Between 18 and 21 weeks: a detailed look at how your baby is growing.You are here · 10w 0d 4 Jan 2027 in 2 months
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Week 24 Sugar test window Between 24 and 28 weeks many clinics check for diabetes in pregnancy.You are here · 10w 0d 1 Feb 2027 in 3 months
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Week 28 Third trimester From 28 weeks: more regular checks, and time to plan the birth.You are here · 10w 0d 1 Mar 2027 in 4 months
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Week 37 Full term From 37 weeks your baby is considered full term.You are here · 10w 0d 3 May 2027 in 6 months
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Week 40 Due date Only about one baby in twenty arrives on the day itself. Most come within two weeks either side.You are here · 10w 0d 24 May 2027 in 7 months
How it works
Three ways to date a pregnancy, one answer
Each method counts back to the same starting point, so they agree with each other. Here is the example worked all three ways.
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01
Last period + 280 days
The way most doctors date a pregnancy. Count 280 days, or 40 weeks, from the first day of your last period. If your cycle is longer or shorter than 28 days, the date moves by the difference.
A period that started on 17 August 2026 gives a due date of 24 May 2027.
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02
Conception date + 266 days
If you know when you conceived, for example from ovulation tests or a timed treatment such as IUI, count 266 days, or 38 weeks, from that day.
Conceiving on 31 Aug 2026 gives the same due date, 24 May 2027.
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03
IVF transfer + 260 to 263 days
After IVF the date is known to the day. Count from the transfer, taking away the age of the embryo: 263 days for a day 3 embryo, 261 for a day 5 blastocyst and 260 for day 6. Fresh and frozen transfers work the same way.
A day 5 transfer on 5 September 2026 gives 24 May 2027 too.
Pregnant after IVF
After IVF, your due date is known to the day
A natural pregnancy is dated from a period, which is a guess about when you ovulated. After IVF there is no guess: the day of fertilisation is on record. That is why IVF due dates are the most precise of all.
| Embryo | On transfer day you are | Due date |
|---|---|---|
| Day 3 | 2 weeks 3 days | Transfer + 263 days |
| Day 5 blastocyst | 2 weeks 5 days | Transfer + 261 days |
| Day 6 blastocyst | 2 weeks 6 days | Transfer + 260 days |
The three trimesters
What each stretch of pregnancy brings
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1
First trimester
Weeks 1 to 13
The baby's organs form and the heartbeat appears. Tiredness and nausea are common. The early and dating scans happen now.
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2
Second trimester
Weeks 14 to 27
Often the easiest stretch. You may feel the first movements, and the anatomy scan checks how everything is growing.
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3
Third trimester
Week 28 to birth
Your baby gains most of their weight. Checks become more frequent and it is time to plan where and how to give birth.
Questions
What people ask about due dates
Trying to get pregnant, or pregnant after treatment? Our specialists are happy to talk it through, and you will know the fee before anything is booked.
Book a consultationHow accurate is a due date?
It is an estimate. Only about one baby in twenty is born on the due date itself, and most arrive within two weeks either side of it. Your dating scan between 11 and 14 weeks may move the date by a few days, and your doctor will then go by the scan.
How is the due date worked out after IVF?
From the day of the embryo transfer. Your pregnancy is counted as if it began two weeks before fertilisation, so a day 5 blastocyst transfer is treated as 2 weeks and 5 days of pregnancy on the day it happens. That is why the calculator adds 261 days to a day 5 transfer, 263 to a day 3 transfer and 260 to a day 6 transfer.
Does a frozen embryo transfer change the calculation?
No. What matters is the age of the embryo when it was transferred, not whether it was frozen first. A frozen day 5 blastocyst is dated exactly like a fresh one.
Why does my cycle length matter?
The standard rule assumes you ovulate on day 14 of a 28 day cycle. With a 35 day cycle you probably ovulated about a week later, so your due date is about a week later too. The calculator adjusts for any cycle from 21 to 45 days.
Why am I already two weeks pregnant at conception?
Pregnancy is counted from the first day of your last period, about two weeks before you conceive. It is a convention that lets every pregnancy be dated the same way, whether or not the day of conception is known.
When will my clinic do the pregnancy test after IVF?
Usually with a blood test about 9 to 12 days after the transfer: sooner after a day 5 or 6 blastocyst, a little later after a day 3 embryo. Your clinic will give you the exact day, and a home test before then can be misleading.
Is my information stored anywhere?
No. The calculation happens in your own browser. The dates you enter are never sent to us, never saved and never added to the page address.
Still on the way there?
Every due date starts with a first conversation.
If you are trying for a baby, our fertility specialists can help you understand your options and your chances.