Pregnancy Weight Gain Target Calculator
How much weight is healthy to gain in pregnancy depends on your weight before pregnancy. The Institute of Medicine (now the National Academy of Medicine) published BMI-based ranges for total recommended weight gain in a singleton pregnancy. Enter your pre-pregnancy height and weight to find your BMI category and the corresponding recommended total gain range. This is general guidance for information only; your own target should be set with your maternity provider.
IOM weight gain ranges
- Underweight, BMI under 18.5: recommended gain 12.5 to 18 kg (28 to 40 lb).
- Normal weight, BMI 18.5 to 24.9: recommended gain 11.5 to 16 kg (25 to 35 lb).
- Overweight, BMI 25.0 to 29.9: recommended gain 7 to 11.5 kg (15 to 25 lb).
- Obese, BMI 30.0 and above: recommended gain 5 to 9 kg (11 to 20 lb).
- Ranges are for a single baby; twin pregnancies have higher recommended gains.
BMI formula and worked example
BMI = weight(kg) / height(m)^2
A 65 kg woman 1.65 m tall has BMI = 65 / (1.65^2) = 65 / 2.7225 = 23.88, in the normal-weight category, so the recommended total gain is 11.5 to 16 kg.
Frequently asked questions
Where do these ranges come from?
They are the 2009 Institute of Medicine (now National Academy of Medicine) recommendations for total weight gain in pregnancy, based on pre-pregnancy BMI. They are endorsed and used widely by maternity care providers.
Do the ranges apply to twins?
No. The ranges shown are for a singleton pregnancy. The Institute of Medicine gives higher provisional ranges for twin pregnancies, and your provider will advise a suitable target if you are expecting more than one baby.
Is weight gain the only thing that matters?
No. The pattern of gain, your diet quality, activity and overall health all matter. These ranges are general targets for information; individual advice should come from your maternity care team.
Sources
- U.S. Centers for Disease Control and Prevention: weight gain during pregnancy.
Reviewed by the CalculatorHub team, edited by James Graham, 19 June 2026. See our methodology.