Pregnancy weight gain calculator
See the recommended total gain for your pre-pregnancy BMI, and roughly where that puts you at a given week.
Where these numbers come from
The total gain ranges are the 2009 Institute of Medicine (now the National Academy of Medicine) pregnancy weight gain guidelines, which remain the standard reference in US prenatal care. They are banded by pre-pregnancy BMI:
- Underweight (BMI under 18.5): 28–40 lb
- Normal weight (18.5–24.9): 25–35 lb
- Overweight (25–29.9): 15–25 lb
- Obese (30 and over): 11–20 lb
Twin pregnancies have their own higher ranges. Note that the IOM did not issue a recommendation for underweight BMI with twins, citing insufficient evidence; where that combination is selected the calculator shows the normal-weight twin range as an approximation and says so.
Gain is not evenly spread
Most guidance expects only one to four and a half pounds across the whole first trimester, then a steadier weekly rate afterwards. Early pregnancy nausea means some people lose weight in the first trimester, which is common and usually not a concern on its own.
Reasons the number may not apply to you
These ranges are population averages for uncomplicated pregnancies. Your own target may differ if you have gestational diabetes, hyperemesis, a thyroid condition, a history of bariatric surgery, or are carrying more than two babies. Your provider may set a different range deliberately, and theirs is the one to follow.
Also useful: the week tracker to confirm which week you are in.