MayoCalc / Health

Pregnancy Weight Gain Calculator

See the recommended healthy weight gain range based on your pre-pregnancy BMI and current week.

Last updated April 2026
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Recommended Total Gain
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Your Progress at Week 20
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Disclaimer: This tool is for general educational and informational purposes only. It does not constitute medical advice, professional diagnosis, or treatment and is not a substitute for consultation with a qualified healthcare provider. No doctor-patient relationship is created by your use of this tool. Results are estimates based on published formulas and population-level data that may not reflect your individual medical circumstances. Neither MayoCalc nor Cook Media Systems assumes any liability or responsibility for damage or injury (including death) to any person arising from the use of any information, results, or content provided by this tool. Always consult your physician or other qualified healthcare provider with any questions about a medical condition. See our full Disclaimer and Terms of Service.

How Much Weight Should You Gain?

Recommended pregnancy weight gain depends on your pre-pregnancy BMI. The Institute of Medicine (IOM, now the National Academy of Medicine) provides these guidelines: Underweight (BMI below 18.5): 28-40 lbs. Normal weight (BMI 18.5-24.9): 25-35 lbs. Overweight (BMI 25-29.9): 15-25 lbs. Obese (BMI 30+): 11-20 lbs. For twin pregnancies, recommended gains are higher: 37-54 lbs for normal weight, 31-50 lbs for overweight, and 25-42 lbs for obese.

How to Use This Calculator

Enter your pre-pregnancy weight, height, and current week of pregnancy. The calculator shows your pre-pregnancy BMI, the recommended total weight gain range, where you should be at your current week, and a week-by-week expected gain chart. Weight gain is not linear: little to no gain in the first trimester (0-4 lbs total), then roughly 1 lb per week in the second and third trimesters for normal-weight women.

Where the Weight Goes

Of the 25-35 lbs of recommended weight gain, only 7-8 lbs is the baby at birth. The rest includes: placenta (1.5 lbs), amniotic fluid (2 lbs), uterine growth (2 lbs), increased blood volume (3-4 lbs), increased breast tissue (1-2 lbs), fat stores for breastfeeding (5-9 lbs), and increased fluid (3-4 lbs). Most of the non-fat weight is lost within weeks of delivery.

Pregnancy Weight FAQ

Is it dangerous to gain too much or too little?
Gaining too much increases the risk of gestational diabetes, preeclampsia, cesarean delivery, and postpartum weight retention. Gaining too little increases the risk of preterm birth and low birth weight. Both carry risks, which is why the IOM provides specific ranges based on pre-pregnancy BMI. Discuss your individual situation with your OB-GYN.
Should I "eat for two"?
Not in terms of calories. In the first trimester, no extra calories are needed. In the second trimester, approximately 340 extra calories per day are recommended. In the third trimester, approximately 450 extra per day. Focus on nutrient-dense foods rather than simply eating more.

Recommended Weight Gain During Pregnancy

The Institute of Medicine (IOM) guidelines for pregnancy weight gain are based on pre-pregnancy BMI: underweight women (BMI below 18.5) should gain 28-40 pounds, normal weight women (BMI 18.5-24.9) should gain 25-35 pounds, overweight women (BMI 25-29.9) should gain 15-25 pounds, and obese women (BMI 30+) should gain 11-20 pounds. For twin pregnancies, recommended ranges are approximately 10-15 pounds higher. These guidelines aim to optimize outcomes for both mother and baby.

Weight gain is not linear throughout pregnancy. In the first trimester, typical gain is 1-5 pounds total (some women lose weight due to nausea). In the second and third trimesters, the recommended rate is approximately 1 pound per week for normal-weight women, 0.5-0.7 pounds per week for overweight women, and 0.4-0.6 pounds per week for obese women.

Where the Weight Goes

For a typical 30-pound pregnancy weight gain: baby accounts for 7-8 pounds, placenta 1.5-2 pounds, amniotic fluid 2 pounds, uterine growth 2 pounds, increased breast tissue 2 pounds, increased blood volume 4 pounds, increased fluid volume 4 pounds, and maternal fat stores 5-9 pounds. The fat stores serve as energy reserves for breastfeeding. Most women lose 10-15 pounds immediately at delivery (baby, placenta, amniotic fluid, blood). Returning to pre-pregnancy weight typically takes 6-12 months, though timelines vary widely. The Due Date Calculator helps track your pregnancy timeline.

Excessive weight gain during pregnancy increases risk of gestational diabetes, preeclampsia, cesarean delivery, and postpartum weight retention. Insufficient weight gain increases risk of preterm birth, low birth weight, and failure to thrive. Women who begin pregnancy at a healthy weight and gain within the recommended range have the lowest rates of pregnancy complications. Regular prenatal visits include weight monitoring, and your healthcare provider will flag any concerning trends. Strategies for healthy weight management during pregnancy include eating nutrient-dense foods, staying physically active (most women can safely continue moderate exercise throughout pregnancy with provider approval), and focusing on hunger and fullness cues rather than calorie counting.

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