Pregnancy Weight Gain Calculator
See the recommended pregnancy weight gain range for your pre-pregnancy BMI, with the expected weekly gain rate for each trimester.
The ranges shown are the widely published US Institute of Medicine / National Academy of Medicine guidance for a single pregnancy, grouped by pre-pregnancy BMI. Guidance differs between countries: UK and NICE advice does not set a target range in the same way and focuses on eating well and staying active rather than on a specific number. Your midwife may adjust the expectation for twins, your starting weight, sickness, or other conditions — their advice comes first.
Frequently asked questions
How much weight should I gain in pregnancy?
It depends on your pre-pregnancy BMI. Guidance from the US Institute of Medicine suggests roughly 11.5 to 16 kg for a healthy starting BMI, less if you start overweight and more if you start underweight.
How much weight should I gain per week?
In the second and third trimesters, about 0.35 to 0.5 kg a week is typical for someone with a healthy starting BMI. Most weight gain happens after the first trimester.
Is this the same as UK guidance?
Not exactly. The UK does not routinely publish a target weight-gain range and instead focuses on healthy eating and monitoring. Treat these figures as general reference points and follow your midwife's advice.
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