Pregnancy Weight Gain Calculator
See your recommended pregnancy weight-gain range by pre-pregnancy BMI and week. Free tool comparing your progress to the guideline range.
About the Pregnancy Weight Gain Calculator
How much weight to gain in pregnancy depends mainly on your weight before pregnancy. This free pregnancy weight gain calculator uses your pre-pregnancy BMI and current week to show the recommended total gain and where you should be by now, then compares it with your current weight so you can see if you are on track.
The ranges follow widely used Institute of Medicine guidance: 12.5-18 kg for underweight (BMI under 18.5), 11.5-16 kg for normal weight (18.5-24.9), 7-11.5 kg for overweight (25-29.9) and 5-9 kg for obese (30+). Most of the gain happens in the second and third trimesters, roughly 0.4-0.5 kg per week for a normal-weight woman.
Expectant mothers use this to understand healthy targets between check-ups. It provides general guidance only and is not medical advice — your doctor or midwife gives personalised recommendations, especially for twins or existing conditions. Everything runs privately in your browser.
How to Use the Pregnancy Weight Gain Calculator
- 1Enter your height and pre-pregnancy weight to find your BMI category.
- 2Enter your current week of pregnancy.
- 3Enter your current weight.
- 4Read the recommended total range and how your progress compares.
Frequently Asked Questions
How much weight should I gain during pregnancy?
It depends on your pre-pregnancy BMI. Normal-weight women (BMI 18.5-24.9) are generally advised to gain 11.5-16 kg total; underweight women more (12.5-18 kg) and overweight or obese women less (7-11.5 kg and 5-9 kg). The calculator selects your range automatically.
How is pregnancy weight gain spread across the trimesters?
The first trimester usually adds little — about 0.5-2 kg. Most gain comes in the second and third trimesters at roughly 0.4-0.5 kg per week for a normal-weight woman. The calculator estimates where you should be for your current week.
What if I am carrying twins?
Recommended gain is higher for twins — often around 17-25 kg for a normal-weight woman — but ranges vary and should be set with your doctor. This calculator uses single-pregnancy guidelines, so treat its numbers as a lower bound for a twin pregnancy.
Is gaining outside the recommended range dangerous?
Gaining too little or too much can raise risks for you and the baby, but individual circumstances differ widely. Small deviations are common and usually fine. Always discuss your weight trend with your healthcare provider rather than adjusting diet drastically on your own.