How it's calculated
From the first day of your last period, the due date is 280 days (40 weeks) later, adjusted if your cycle isn't 28 days. From conception it's 266 days; from a day-5 IVF transfer it's 261 days.
Key milestones
The tool also shows the end of the first trimester, the start of the third trimester and when full term begins.
Frequently asked questions
How accurate is a due date?
Only about 5% of babies arrive on their due date; most are born within two weeks either side. An early ultrasound can refine the estimate.
Is this medical advice?
No. Always confirm dates and care with your doctor or midwife.
Related tools
Fabric & Sewing Measurement Converter
Convert between yards, metres, inches and cm, and estimate how much fabric to buy.
Aquarium Volume Calculator
Work out your tank's volume, water weight and water-change amounts.
Running Pace Calculator
Calculate pace, finish time and predicted race times.
Tattoo Size Estimator
Convert a tattoo's size and see how it compares with common body placements.
Tire Size Calculator
Compare two tyre sizes: diameter, sidewall height and speedometer error.