Pregnancy Calculator
Find out how far along you are, your due date and your trimester, plus a week-by-week schedule of the main tests and milestones with the dates they fall on for you.
How this pregnancy calculator works
Doctors count pregnancy from the first day of your last menstrual period (LMP), not from conception. A typical pregnancy lasts 280 days, or 40 weeks, from the LMP. The calculator uses that rule and adjusts it in these ways:
Last period: due date = LMP + 280 days, plus or minus the difference between your cycle length and 28 days.
Conception date: due date = conception + 266 days.
IVF transfer: due date = transfer + 261 days for a day-5 embryo, or + 263 days for a day-3 embryo.
Due date: if you already know it (for example from an ultrasound), the calculator works backward from it.
The three trimesters
First trimester (weeks 1 to 13): the baby's organs begin to form. Nausea and tiredness are common.
Second trimester (weeks 14 to 27): many women feel more energetic, and the first baby movements are usually felt between weeks 16 and 22.
Third trimester (weeks 28 to birth): the baby gains most of its weight and gets into position for birth.
Frequently asked questions
How accurate is my due date?
It is an estimate. Most babies are born between 38 and 42 weeks. An early ultrasound, done in the first trimester, is the most accurate way to date a pregnancy, so your doctor may adjust the date after your first scan.
Why am I already 2 weeks pregnant at conception?
Because pregnancy is counted from the first day of your last period, and conception usually happens about two weeks later, around ovulation.
What if my cycle is irregular?
The LMP method is less reliable with irregular cycles. If you know your conception date or have an ultrasound date, choose that method instead.
This calculator gives general estimates for educational purposes and is not medical advice. Test timings vary by country and clinic; follow the schedule your doctor or midwife gives you.