Pregnancy Calculators: Due Date, How Far Along You Are, and More
Pick the right calculator for what you already know. They all use the same guideline-based formulas, so their results agree with each other, and nothing you enter leaves your browser.
Which calculator do you need?
I know the date of my last period. When is my baby due?
Due date calculator: your estimated due date, how far along you are today and your full-term window.
I have a due date. How many weeks am I now?
Pregnancy week calculator: works out your current week and trimester from the date your provider gave you.
When did I conceive?
Conception date calculator: works backwards from your due date or last period to an estimated conception date.
I had IVF.
IVF due date calculator: uses your embryo transfer date and embryo age. Don’t use a period-based calculation in this case.
I’m trying to get pregnant.
Ovulation calculator: estimates your most fertile days from your cycle.
How much weight should I gain?
Pregnancy weight gain calculator: shows the recommended range based on your pre-pregnancy weight.
Is my hCG level normal?
hCG levels: calculates and explains the rise and doubling time between two tests.
Why every result is an estimate
All pregnancy calculations start from the same assumption: pregnancy is counted from the first day of your last period and lasts about 280 days. In reality, the day you ovulate varies from person to person and even month to month. So a calculator gives you a good idea of the timing, and a first-trimester ultrasound measurement sets the date for certain.
If your provider has adjusted your due date based on a scan, use that date in every calculator from now on. Because our calculators share the same formulas, they’ll all give consistent results with the adjusted date.
Frequently asked questions
Which calculation is the most accurate?
If your periods are regular, dating from your last period is a good starting point. With IVF the transfer date is known exactly, so that's the most reliable calculation. In every case, a first-trimester ultrasound measurement is the most accurate way to date a pregnancy.
Can a calculator replace an ultrasound?
No. Calculators give an estimate, and your provider may adjust your due date based on an early ultrasound. If your date has been adjusted, use the adjusted date in our calculators too.
Are the dates I enter saved anywhere?
No. All calculations happen in your browser; nothing you enter is sent to us or stored.
About this page
- Medical review
- Emergency medicine physician · October 24, 2026
- Last updated
Sources
- Methods for Estimating the Due Date. Committee Opinion No. 700. American College of Obstetricians and Gynecologists (ACOG), 2017.
This page is for general information and does not replace an examination or diagnosis.