Pregnancy Weight Gain Calculator

Recommended pregnancy weight gain by BMI

The ranges below align with the guidance used by calculator.net, based on the Institute of Medicine recommendations. Use your pre-pregnancy BMI to find your category, then compare single and multiple pregnancy ranges.

How to use the weekly ranges

Most of the steady gain happens in the second and third trimesters. If you are tracking week to week, compare your total gain to the calculator's trimester breakdown and focus on trends over several weeks instead of day-to-day fluctuations.

FAQ

• How does the calculator decide the recommended range? We use the Institute of Medicine guidance that calculator.net references, based on pre-pregnancy BMI categories and whether you are carrying a single baby or multiples.
• Why is the first trimester range smaller? Most people gain only 1–4.5 lb in the first trimester because energy needs are lower early on and nausea may reduce intake.
• What if I do not know my pre-pregnancy BMI? Switch to height and weight mode to estimate your BMI using your pre-pregnancy measurements, then use that result for the calculator.
• Does the weekly range apply after week 40? The calculator follows the 40-week pregnancy model. If you go past 40 weeks, ask your clinician how much additional gain is appropriate.
• Is weight gain guidance different for twins? Yes. Total gain targets are higher for multiple pregnancies. Weekly ranges are estimated by spreading that total across weeks 14–40.
• Is this medical advice? No. This calculator is for education only. Always check with your prenatal care team for personalized guidance.