Pregnancy Weight Gain Calculator
How much weight to gain during pregnancy for your pre-pregnancy BMI, and the typical gain by the week you're in.
Total gain to aim for
11.5 to 16 kg
- Typical gain by week 24
- 4.4 to 7.5 kg
- From week 14, per week
- 0.35 to 0.5 kg
- Pre-pregnancy BMI
- 23.4 normal weight
Starting at a BMI of 23.4 (normal weight), the usual target is 11.5 to 16 kg in total. By week 24, a typical gain is 4.4 to 7.5 kg.
How it's worked out
- BMI before pregnancy
60 ÷ 1.6²23.4 (normal weight) - Recommended total
IOM 2009, one baby11.5 to 16 kg
- General guidance from the US Institute of Medicine. Your doctor or midwife may set a different target for you.
How it's worked out
Your BMI before pregnancy sets the target range (US Institute of Medicine, 2009). The typical gain by your week assumes 0.5 to 2 kg in the first 13 weeks, then the recommended weekly rate.
Worked example
At 60 kg and 160 cm, BMI was 23.4, a healthy weight, so the target is 11.5 to 16 kg. By week 24, a typical gain is about 4.4 to 7.5 kg.
Questions people ask
How much weight should I gain in pregnancy?
It depends on your BMI before pregnancy: 12.5 to 18 kg if underweight, 11.5 to 16 kg at a healthy weight, 7 to 11.5 kg if overweight and 5 to 9 kg if obese, for one baby.
How much weight is gained in the first trimester?
Usually only 0.5 to 2 kg. Most of the gain comes in the second and third trimesters.
How much should I gain with twins?
The provisional guidance is 17 to 25 kg at a healthy weight, 14 to 23 kg if overweight and 11 to 19 kg if obese. The Institute of Medicine sets no target for twins when starting underweight; the US CDC shows 23 to 28 kg from a separate study.
About this calculator
Formula and rules last checked 12 November 2026Written and tested by the CalculatorDex teamReport a problem
Sources: Institute of Medicine and National Research Council (2009), Weight Gain During Pregnancy: Reexamining the Guidelines · CDC, Weight Gain During Pregnancy