Pregnancy Weight Gain Calculator

The Pregnancy Weight Gain Calculator helps you see whether your weight gain during pregnancy is tracking within the commonly cited 2009 Institute of Medicine (IOM/NASEM) recommendations.

Those guidelines tie the healthy total gain to your pre-pregnancy body mass index: people who started underweight are advised to gain more, while those who started overweight or obese are advised to gain less.

Enter your pre-pregnancy weight, height, current weight and how many weeks along you are, and the tool works out your starting BMI, the total range recommended for the whole pregnancy, and roughly how much you would be expected to have gained by your current week.

It accounts for the slower gain typical of the first trimester and the steadier weekly accrual that follows, then tells you whether your gain so far sits below, within or above the suggested band.

You can switch between kilograms and pounds, and a twins option swaps in the higher ranges recommended for twin pregnancies.

This is an educational estimate, not medical advice: every pregnancy is different, and your provider may set a different target based on your individual health.

All calculations run locally in your browser — none of your figures are uploaded or stored — so your information stays private, and the tool works offline once loaded.