Due Date Calculator

Only about 4% of babies arrive on their due date; most arrive within two weeks either side. If your first ultrasound measurement differs from your period-based date by more than about 7 days in the first trimester, your care team will usually change your due date to the scan date. Once set by an early scan, the due date is not normally changed again by later scans.

All four methods rest on the same idea: a pregnancy lasts about 280 days from the first day of your last period. They just start from different known points.

• Last period (LMP) works well if your cycles are regular and you're sure of the date. If your cycle is longer or shorter than 28 days, adjusting for cycle length makes the estimate more accurate, because ovulation happens later or earlier.
• Conception date is useful if you tracked ovulation or know exactly when you conceived. Sperm can survive several days, so the date of sex and the date of conception can differ.
• IVF transfer is the most precise of the date-based methods, because the embryo's age and the transfer date are known exactly.
• Ultrasound in the first trimester is the most reliable way to date a pregnancy when the period date is uncertain. Measurements of the baby's crown–rump length up to about 13+6 weeks are accurate to within roughly a week. Later scans are less precise for dating because babies start to grow at different rates.

If you have more than one date, your care team will usually choose the one from your earliest ultrasound if it differs meaningfully from your period date.

Your due date is the middle of a window, not a deadline. Most babies are born between 37 and 42 weeks, and only a small minority arrive on the exact day. Think of it as a planning date: it tells you when your appointments fall, when to finish work, and when to have your bag ready.

It's also normal to feel impatient as the date approaches, or anxious if it passes. Going past your due date is common, especially in first pregnancies. Your care team will offer extra monitoring and talk through options such as a membrane sweep or induction, usually from around 41 weeks.

The timeline turns your due date into real calendar dates for the moments that matter: your first appointment, screening windows, the anomaly scan, the glucose test, the start of each trimester, and the full-term window. Add them to your phone calendar with one tap and each reminder arrives the day before.

Tap Save as my pregnancy and the Trimester Tracker, Weight Gain Calculator and Kick Counter will fill in automatically. Everything stays on your device; nothing is uploaded.

Appointment schedules vary between hospitals, clinics and countries. Treat the dates as a guide and follow the plan your doctor or midwife gives you.

Once you have a date, a few practical things become easier to plan. Many people tell their employer around the end of the first trimester and start thinking about leave dates in the second. In Singapore, working parents of a Singapore citizen baby born on or after 1 April 2026 can get up to 30 weeks of government-paid leave in the first year: 16 weeks of maternity leave, 4 weeks of paternity leave and 10 weeks of shared parental leave, split between you. Antenatal classes often book up early, so the second trimester is a good time to choose one. By around 36 weeks, aim to have your hospital bag packed, the car seat fitted and your route to hospital planned, because the full-term window begins at 37 weeks. If you have other children or pets, arrange back-up care that can start at short notice.

If you're travelling during pregnancy, check your airline's rules: many ask for a doctor's letter later in pregnancy and restrict flying in the final weeks.

If you're pregnant in Singapore, your timeline will look roughly like the one KKH gives its patients. Use your due date from this calculator to put real dates on each step:

• 8–12 weeks: first visit, routine blood tests and a dating scan to confirm your due date.
• 11–14 weeks: optional first-trimester screening for Down syndrome (a blood test plus ultrasound).
• 18–21 weeks: the detailed "20-week" anomaly scan, which checks your baby from head to toe.
• 24–28 weeks: screening for anaemia and gestational diabetes. Whooping cough vaccination is also recommended around this time.
• 28–32 weeks: a growth scan to check your baby's size and wellbeing.
• 35–37 weeks: a Group B Strep swab.

Many mums start antenatal care at a polyclinic. NHG polyclinics, for example, see you every four weeks until 28 weeks, every two weeks after that, and refer you to the hospital for scans and for the final weeks (usually from about 34 weeks). Private obstetricians follow a similar plan with their own schedule. Whichever route you choose, the dates in your timeline are a guide; your clinic's appointment card is the plan to follow.