Pregnancy week calculator
Let's find out how far along you are!
Calculate your pregnancy week with our pregnancy calculator
Curious about your current stage of pregnancy? Use our pregnancy calculator to determine your pregnancy week in four different ways.
How to calculate your pregnancy week
The most common way to calculate your pregnancy week, before an ultrasound, is by counting from the first day of your last period. However, other methods are available depending on how you conceived and the information you have.
Pregnancy length is typically calculated from the start of the cycle in which conception occurred, including the time before ovulation and fertilization.
Example: If two weeks and three days have passed since fertilization, you would be considered 4 weeks + 3 days pregnant.
Calculate the week based on your last period
If you know the first day of your last period and the usual length of your cycle, you can use this information to estimate your current pregnancy week.
Calculate pregnancy week based on conception
If you have a rough idea of when conception occurred, you can use that date to estimate your pregnancy week. Fertilization occurs within 24 hours of ovulation, as the egg survives only that long. However, sperm can live in the body for up to six days, meaning fertilization may happen later if ovulation occurs afterward.
Calculate pregnancy with IVF
If you've undergone IVF treatment, you can determine your pregnancy week by entering the date of embryo transfer and the embryo’s age at that time.
Example: If a 5-day blastocyst was transferred, the transfer date would correspond to pregnancy week 2+5.
Determine your pregnancy week based on an ultrasound
If you’ve had an ultrasound confirming your pregnancy week, you can use this information along with the date of the ultrasound to calculate your current pregnancy week.