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Healthy pregnancy weight gain ranges vary by pre-pregnancy BMI category, based on guidelines from the Institute of Medicine (IOM) — this calculator is for general information only and is not a substitute for guidance from your doctor or midwife.
This calculator estimates your BMI category and the recommended total weight gain range, plus an approximate gain-to-date figure.
How it works
Enter your pre-pregnancy weight, height, and current week of pregnancy. The calculator finds your pre-pregnancy BMI category, looks up the IOM-recommended total gain range for that category, and estimates a proportional gain-to-date based on your current week.
- Enter pre-pregnancy weight (kg).
- Enter height (cm).
- Enter current week of pregnancy.
- Click Calculate to see your results.
Examples
Normal BMI, week 20
A person with a normal pre-pregnancy BMI at week 20 of pregnancy has a recommended total gain range of 25-35 lbs, with an approximate gain-to-date of about 15 lbs.
Who should use it
- General educational reference for typical pregnancy weight gain ranges.
- A starting point for conversation with a healthcare provider about weight gain goals.
Industry applications
- Prenatal health education
- General wellness tracking
Advantages
- Uses published, widely referenced IOM guideline ranges.
- Provides both a total range and an approximate gain-to-date figure.
Limitations
- The gain-to-date approximation is linear and doesn't reflect the actual non-linear pattern of pregnancy weight gain by trimester.
Common mistakes to avoid
- Treating the gain-to-date estimate as a precise target rather than a rough, linearly-approximated reference.
- Using this tool as a substitute for prenatal care instead of a general educational reference.
Best practices
- Discuss your specific healthy weight gain target with your doctor or midwife, especially if you have a multiple pregnancy or pre-existing health conditions not reflected in general BMI-based guidelines.
Tips
- Weight gain naturally varies week to week — focus on the overall trend across your pregnancy rather than any single week's number, and always loop in your healthcare provider with concerns.