Find your recommended total and weekly pregnancy weight gain based on pre-pregnancy BMI. Uses IOM guidelines for all BMI categories.
Before you start tracking weekly weight gain, you need to know your target range. This calculator takes your pre-pregnancy height and weight, calculates your BMI, and instantly provides the IOM-recommended total weight gain range and the suggested weekly gain rate for the second and third trimesters.
The Institute of Medicine's 2009 guidelines remain the gold standard for pregnancy weight gain recommendations. They account for the well-established relationship between pre-pregnancy BMI and optimal pregnancy outcomes. Women who gain within their recommended range have lower rates of gestational diabetes, preeclampsia, cesarean delivery, and neonatal complications.
This tool provides a quick reference that you can discuss with your healthcare provider at your first prenatal visit to set personalized weight gain goals. Whether you are a beginner or experienced professional, this free online tool provides instant, reliable results without manual computation. By automating the calculation, you save time and reduce the risk of costly errors in your planning and decision-making process.
Setting clear weight gain expectations from the start of pregnancy helps you make informed nutrition and activity choices. Knowing your specific range — based on your starting BMI — removes guesswork and provides a measurable goal for each trimester. Having a precise figure at your fingertips empowers better planning and more confident decisions.
BMI = (weight_lbs / height_in² ) × 703 IOM Recommendations by BMI: Underweight (< 18.5): 28-40 lbs total, 1.0-1.3 lbs/week Normal (18.5-24.9): 25-35 lbs total, 0.8-1.0 lbs/week Overweight (25-29.9): 15-25 lbs total, 0.5-0.7 lbs/week Obese (≥ 30): 11-20 lbs total, 0.4-0.6 lbs/week
Result: BMI 22.3 (Normal) — Gain 25-35 lbs total
At 5'4" and 130 lbs, the pre-pregnancy BMI is 22.3, which falls in the normal category. The recommended total gain is 25-35 lbs. During the second and third trimesters, the target is 0.8-1.0 lbs per week. In kilograms, that is 11.5-16 kg total and 0.36-0.45 kg per week.
Pre-pregnancy BMI is classified as underweight (< 18.5), normal (18.5-24.9), overweight (25-29.9), or obese (≥ 30). Each category has a specific recommended weight gain range that balances fetal growth needs with maternal health considerations.
Total weight gain is the headline number, but weekly gain rate is more actionable for day-to-day management. The weekly rates apply primarily to the second and third trimesters, when fetal growth is most rapid. First-trimester gain is minimal and highly variable.
Discuss your weight gain target with your provider at the first prenatal visit. Write it down. At each subsequent visit, your provider will track your actual gain against the target. If you fall outside the range, dietary counseling or additional monitoring may be recommended.
Women with different starting BMIs have different metabolic needs and risks. Underweight women benefit from more weight gain to support the baby, while obese women already have energy reserves and excessive gain adds risk for complications like gestational diabetes.
If your BMI is near a boundary (e.g., 24.8 or 25.1), discuss with your provider. They may recommend a target in between the two ranges based on your overall health profile.
The IOM guidelines were published in 2009 and have been widely validated. Some researchers suggest adjustments for higher BMI categories, but as of 2026, these remain the official recommendations endorsed by ACOG.
The IOM uses a single category for all BMI ≥ 30. Some providers recommend lower targets (10-15 lbs) for very obese women. This should be individualized with your care team.
Divide pounds by 2.2 to get kilograms. For example, 25 lbs is about 11.3 kg and 35 lbs is about 15.9 kg. The calculator shows both units.
Exercise is encouraged during pregnancy and may help you gain within the recommended range. It does not change the target itself, but it improves cardiovascular fitness, mood, and postpartum recovery.