Pregnancy Weight Gain Calculator
Select your pre-pregnancy BMI category to see the total pregnancy weight gain range recommended by standard Institute of Medicine (IOM) guidelines.
Recommended total gain
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Select a category to see the recommended range.
How the Pregnancy Weight Gain formula works
Standard IOM total weight gain guidelines for a single pregnancy:
Underweight (BMI < 18.5): 28–40 lb Normal weight (18.5–24.9): 25–35 lb Overweight (25–29.9): 15–25 lb Obese (30+): 11–20 lb
Step-by-step calculation
- Determine your pre-pregnancy BMI category (use the BMI Calculator if needed).
- Match that category to its recommended total weight gain range for a full-term single pregnancy.
Worked example
Someone with a pre-pregnancy BMI of 23 (normal weight category) has a recommended total pregnancy weight gain range of 25–35 pounds over the full pregnancy.
Frequently asked questions
Do these ranges apply to twin or multiple pregnancies?
No — these guidelines are for a single (singleton) pregnancy. Twin and multiple pregnancies have separate, higher recommended ranges, and should be discussed with a healthcare provider.
Is weight gain distributed evenly throughout pregnancy?
No — most guidelines suggest a smaller gain (around 1–4.5 lb total) during the first trimester, with the majority of weight gain occurring more steadily during the second and third trimesters.