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Pregnancy Due-Date Calculator
Work out your estimated due date (EDD) from your last period, conception or ovulation date, IVF transfer, a dating scan, or a due date you already know. See how far along you are, your trimester, key pregnancy milestones with calendar dates, and a few fun facts about your baby. Built for Singapore mums.
Estimated due date
Your pregnancy this week
Your pregnancy milestones
Key dates worked out from your estimate, using the standard 40-week timeline. A ✓ means the milestone has already passed.
| Milestone | When | Date |
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A few fun facts about your baby
Just for fun. The Chinese zodiac is approximate as it changes at Lunar New Year, not on 1 January.
How the due date is calculated
A full-term pregnancy is counted as 40 weeks (280 days) from the first day of your last period. This is known as Naegele's rule, and it is how doctors in Singapore and around the world estimate a due date when they don't have a scan yet.
Here is what each method on this calculator does:
- Last period (LMP): due date = first day of last period + 280 days, adjusted if your cycle is longer or shorter than 28 days.
- Conception or ovulation date: due date = conception date + 266 days (38 weeks), because conception usually happens about two weeks after your period starts.
- IVF transfer: due date = transfer date + 261 days for a Day-5 blastocyst, + 263 for a Day-3 embryo, + 260 for a Day-6 blastocyst.
- Ultrasound scan: we use the gestational age the scan gave you to work back to your dating LMP, then add 280 days.
- Known due date: we work backwards from your due date to show your milestones and how far along you are.
Why am I "2 weeks pregnant" before I conceived?
Pregnancy is dated from the first day of your last period, not from conception. Because you usually ovulate and conceive about two weeks later, your "gestational age" is roughly two weeks ahead of how long the baby has actually been growing. It sounds odd, but it keeps everyone using the same yardstick.
How accurate is a due date?
Only about 4 to 5 percent of babies arrive on their exact due date, but around 80 percent are born within two weeks either side. A pregnancy is considered to last anywhere from 37 to 42 weeks. Treat the date as your baby's "due month", not a deadline.
Can my due date change?
Yes. Your first-trimester dating scan (usually around 11 to 14 weeks in Singapore) is more accurate than counting from your last period, especially if your cycle is irregular or you are not sure of your dates. If the scan differs from your LMP date by more than a few days, your O&G will usually update your due date to the scan.
What are the trimesters?
- First trimester: weeks 1 to 13.
- Second trimester: weeks 14 to 27.
- Third trimester: week 28 until your baby is born (around week 40).
What to do next in Singapore
Once you have an estimated due date, a few things are worth lining up:
- Book your first O&G appointment and dating scan. Most mums see a private O&G or book in at KKH, NUH, SGH or a polyclinic for shared care. The dating scan around 11 to 14 weeks also covers the first-trimester screening (OSCAR).
- Note your key scan windows: the dating/OSCAR scan (11 to 14 weeks) and the detailed anomaly scan (around 20 weeks).
- Plan the money side early. Work out your hospital and delivery costs and the government support you'll receive with our delivery cost comparison and Baby Bonus, CDA and MediSave estimator.
- Look ahead. Bookmark our childhood vaccination schedule and milestone tracker for after baby arrives.
Frequently asked questions
How is my due date calculated?
The common method (Naegele's rule) adds 280 days, or 40 weeks, to the first day of your last menstrual period. If your cycle is longer or shorter than 28 days, the estimate shifts because ovulation happens later or earlier.
How many weeks pregnant am I right now?
Enter your last period, conception date or due date above and the calculator shows your current gestational age in weeks and days, your trimester, and a progress bar. It updates to today's date automatically.
How accurate is a due date from my last period?
It is a good estimate for regular cycles, but a first-trimester dating ultrasound is more accurate. Only about 5 percent of babies are born on their exact due date, and roughly 80 percent arrive within two weeks either side.
What if I conceived through IVF?
Choose the IVF transfer option and select your embryo age. The due date is based on the transfer date plus the embryo's age: a Day-5 blastocyst is 261 days, a Day-3 embryo 263 days, and a Day-6 blastocyst 260 days. Your clinic's date is the definitive one.
Can my due date change after a scan?
Yes. Your dating scan (around 11 to 14 weeks in Singapore) is more accurate than counting from your last period. If it differs by more than a few days, your O&G will usually update your due date to match the scan.
When is my dating scan and anomaly scan in Singapore?
The dating scan and first-trimester screening (OSCAR) are usually done between 11 and 14 weeks. The detailed anomaly scan is around 20 weeks. The milestone table above shows your personal calendar dates for these windows.
What does "full term" mean?
Doctors now describe term in bands: early term is 37 to 38 weeks, full term is 39 to 40 weeks, late term is 41 weeks, and post-term is 42 weeks and beyond. Most healthy single pregnancies deliver between 39 and 41 weeks.
Is twins or multiples different?
Yes. Twins arrive earlier on average (around 35 to 37 weeks) and triplets earlier still. This calculator estimates a single-baby due date, so follow your O&G's guidance if you are expecting more than one.
