Pregnancy Calculator — Due Date, Weeks, Months & Days
Every pregnancy question in one place. Choose how you want to date the pregnancy, add your details, and see the due date, how far along you are, your trimester, baby's size, important scan dates and a full week-by-week calendar.
Questions women ask most
How is the due date calculated?
The standard (Naegele) rule adds 280 days — 40 weeks — to the first day of your last menstrual period. If your cycle is longer or shorter than 28 days, the date moves by the difference. Only about 4–5% of babies arrive exactly on the due date; most arrive between 37 and 42 weeks.
Which method is most accurate?
An IVF transfer date is the most precise because the embryo's age is known. A first-trimester ultrasound (before 14 weeks) is the next most accurate, within about 5–7 days. LMP dating works well for regular cycles.
How many months pregnant am I?
Pregnancy is 40 weeks, about 9 calendar months plus one week. The calculator shows both the exact calendar months elapsed and which month of pregnancy you are in.
When are twins usually born?
Twins arrive on average around 36 weeks and triplets around 32 weeks, so the calculator shows an adjusted expected delivery date alongside the standard due date.
Is this a medical diagnosis?
No. These are standard dating estimates for planning. Your doctor or midwife will confirm dates with an ultrasound and clinical exam.