Tools · Pregnancy
Pregnancy Weight Gain Calculator
Free pregnancy weight gain calculator. Enter your pre-pregnancy height and weight to see the recommended total weight gain range for your pregnancy.
Enter your pre-pregnancy height and weight to see your recommended range.
For singleton pregnancies only. Always follow your own care provider's guidance, which accounts for your individual health history.
How the Recommended Range Is Calculated
This calculator first works out your pre-pregnancy BMI (weight in kg divided by height in meters squared), then applies the widely referenced weight gain ranges by BMI category: about 12.5–18 kg total for underweight (BMI under 18.5), 11.5–16 kg for a normal starting BMI (18.5–24.9), 7–11.5 kg for overweight (25–29.9), and 5–9 kg for obese (30 and above).
These ranges describe healthy total gain across a full singleton pregnancy, with most of that gain happening in the second and third trimesters rather than the first.
Frequently Asked Questions
Why does the recommended weight gain range depend on pre-pregnancy BMI?
Weight gain guidelines are set relative to your starting body mass index because the underlying goal — supporting healthy fetal growth while limiting risks associated with too little or too much gain — depends on where you started. People who begin pregnancy underweight are generally advised to gain more, and those who begin at a higher BMI are advised to gain less.
Where do these ranges come from?
The ranges used here reflect the widely referenced guidelines from the US Institute of Medicine (IOM, now the National Academy of Medicine), which are commonly cited internationally, though some countries or providers use slightly different figures. Always follow your own care provider's guidance, which accounts for your individual health history.
Is weight gain spread evenly across pregnancy?
No — gain is typically slower in the first trimester (sometimes very little, or even a slight loss with nausea) and picks up in the second and third trimesters. The rate-per-week figures in guidelines specifically describe the second and third trimester pace, not the first.
Do these ranges apply to twin or multiple pregnancies?
No — twin and higher-order multiple pregnancies have separate, higher recommended weight gain ranges. This calculator is for singleton pregnancies only; talk to your care provider for guidance specific to a multiple pregnancy.
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