Pregnancy Weight Gain Guide
Recommended weight gain by week for your starting BMI. Free, private and instant.
How to use the Pregnancy Weight Gain
- Pick metric (cm, kg) or imperial (ft, in, lb) units.
- Enter height.
- Enter weight before pregnancy.
- Enter weeks pregnant.
- Choose pregnancy: One baby or Twins.
- Enter weight now (optional) - optional.
- Press Calculate to get an instant result with a colour scale, chart and plain-English explanation.
About the Pregnancy Weight Gain
The healthy amount of weight to gain in pregnancy depends on your weight before pregnancy. This guide uses Institute of Medicine recommendations to show your recommended gain by week, for one baby or twins, and compares it with your current weight.
Also known as: pregnancy weight gain calculator, how much weight to gain in pregnancy, IOM pregnancy weight gain, twin pregnancy weight gain.
Worked example
- Height: 170 cm
- Weight before pregnancy: 70 kg
- Weeks pregnant: 20 weeks
- Pregnancy: One baby
Advised gain by week 20: 3.4 - 5.6 kg (Advised total 11.5 - 16.0 kg). With a pre-pregnancy BMI of 24.2 (healthy weight), the recommended total gain is 11.5 kg to 16.0 kg. By week 20 that is about 3.4 kg to 5.6 kg.
- Your BMI before pregnancy: 24.2 (healthy weight)
- Total gain advised: 11.5 kg - 16.0 kg
- Advised by week 20: 3.4 kg - 5.6 kg
- Weekly gain (2nd & 3rd trimester): 0.35-0.50 kg
Formula and cut-offs
Recommended total gain: underweight 12.5-18 kg, healthy 11.5-16 kg, overweight 7-11.5 kg, obese 5-9 kg (single baby). Twins: 17-25 kg (healthy), 14-23 (overweight), 11-19 (obese). First trimester gain 0.5-2 kg.
Frequently asked questions
How much weight should I gain in pregnancy?
For a healthy BMI, 11.5 to 16 kg (25 to 35 lb) with one baby. Less is advised if you started overweight.
How much weight do you gain in the first trimester?
Usually only 0.5 to 2 kg (1 to 4.5 lb).
What if I am gaining too fast or too slowly?
Talk to your doctor or midwife. Do not diet in pregnancy; focus on nutritious food and activity.
How much weight should I gain by 20 weeks if I weighed 70 kg before pregnancy and I am 170 cm tall?
Advised gain by week 20: 3.4 - 5.6 kg (Advised total 11.5 - 16.0 kg). With a pre-pregnancy BMI of 24.2 (healthy weight), the recommended total gain is 11.5 kg to 16.0 kg. By week 20 that is about 3.4 kg to 5.6 kg. Enter your own numbers above for a personal result.
Sources and references
- ACOG Committee Opinion 700 - Methods for estimating the due date
- Institute of Medicine (2009) - Weight Gain During Pregnancy: Reexamining the Guidelines
- NHS - Pregnancy guide
Written and checked by the MediHub editorial team against the sources above. Read how we build and review our calculators.
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Last updated . This calculator is for education only and is not medical advice. See the medical disclaimer.