Pregnancy weight gain calculator by week and BMI
Compare your pregnancy weight gain with the IOM range for your BMI before pregnancy, week by week, in kg or lb, with total ranges for one baby and for twins.
How much weight should I gain in pregnancy?
It depends on your BMI before pregnancy. The IOM ranges for one baby run from 5–9 kg (11–20 lb) with a BMI of 30 or more to 12.5–18 kg (28–40 lb) with a BMI under 18.5.
How much weight is usual in the first trimester?
About 0.5 to 2 kg (1 to 4.5 lb). A small loss is common, often with sickness.
What about twins?
The IOM gives provisional ranges for the whole pregnancy, for example 17–25 kg (37–54 lb) with a BMI of 18.5 to 24.9. There's no week-by-week twin band.
Can I use pounds?
Yes. Switch to lb and ft, and everything you've typed is converted.
I'm over or under the range. What now?
It's a guide, not a target. Your midwife or doctor can talk it through with you.
Should I weigh myself every day?
There's no need. Once a week at the same time of day is plenty if you want to track it.
What if I gain weight suddenly, with swelling?
Call your midwife or maternity unit now, especially with a headache, vision problems or pain below your ribs.
Is my data saved?
No. Everything is worked out in your browser and nothing is stored or sent.