Find out how many weeks and days pregnant you are right now. Enter the first day of your last period, or your estimated due date, to see your current week, trimester, percentage complete and the days left to 40 weeks.
Choose a method and enter a date.
This tool gives an estimate only and is not medical advice. The dating used by your healthcare provider, usually confirmed by a scan, takes precedence.
Gestational age is counted from the first day of the last period, so it runs about two weeks ahead of the time since conception.
About this calculator
How far along a pregnancy is, called the gestational age, is counted in weeks and days from the first day of the last menstrual period. A pregnancy is considered full term at 37 weeks, and the due date is set at 40 weeks. This calculator works out your current week and day from either the first day of your last period or your estimated due date. It also shows the share of the 40 weeks that has passed, the days left to reach 40 weeks, and the trimester you are in.
Gestational age is measured from the last period rather than from conception, which means it runs about two weeks ahead of the actual age of the baby. This is a deliberate medical convention, since the last period is a date most people can identify. The percentage complete is a simple share of the standard 40 weeks and is meant as a friendly progress figure, not a prediction of the birth date, because babies arrive across a range of weeks. The NHS, March of Dimes and the American College of Obstetricians and Gynecologists publish week-by-week pregnancy guides.
Frequently asked questions
How many weeks pregnant am I?
Your number of weeks pregnant, the gestational age, is counted from the first day of your last menstrual period, not from conception. This calculator works it out from either that date or your estimated due date and shows it as weeks and days, for example 19 weeks and 4 days. Counting from the last period is the standard medical method, so it matches how a midwife or doctor describes the stage of a pregnancy.
Why is pregnancy counted from the last period?
Pregnancy is dated from the first day of the last menstrual period because that is a day most people can identify, while the exact day of conception usually cannot be known. Conception happens around two weeks into the cycle, so this method counts a pregnancy as roughly two weeks further along than the time since conception. A full-term pregnancy is therefore described as 40 weeks even though the baby has been developing for about 38.
What does the percentage complete mean?
The percentage is a simple progress figure: how much of a standard 40-week pregnancy has passed so far. At 20 weeks it shows about 50 per cent. It is meant as a friendly milestone, not a forecast of the birth date. Babies arrive across a range of weeks, and a pregnancy is full term from 37 weeks, so reaching 100 per cent on the calculator is not a deadline. It simply marks the 40-week point the due date is set at.
How many days until my due date?
The calculator shows the days left to reach 40 weeks, which is the point your estimated due date is set at. It is a countdown to the due date, not a prediction of the actual birth day. Only a small share of babies are born exactly on the due date; most arrive in the surrounding weeks, and a birth any time from 37 weeks is considered full term. Treat the number as a guide to the stage you have reached.
Is this the same as a due date calculator?
It is closely related but answers a different question. A due date calculator works out the date a pregnancy is expected to reach 40 weeks. This calculator starts from that information and tells you where you are today: the current week and day, the trimester, the percentage complete and the days remaining. If you do not yet know your due date, the pregnancy due date calculator can work it out first, and this page then tracks the progress.