Pregnancy Weight Gain Calculator

It depends on your pre-pregnancy BMI. The Institute of Medicine recommends 12.5–18 kg (28–40 lb) for underweight women, 11.5–16 kg (25–35 lb) for normal weight, 7–11.5 kg (15–25 lb) for overweight, and 5–9 kg (11–20 lb) for obese women in singleton pregnancies.

Most women gain very little weight in the first trimester — typically 0.5–2 kg (1–4.5 lb) total across all 13 weeks. Significant weight gain usually starts in the second trimester.

After the first trimester, healthy weekly gain ranges from about 0.22 kg/week (obese BMI) to 0.51 kg/week (underweight BMI). The calculator above shows your specific range.

Twin pregnancies require more weight gain. IOM provisional guidance recommends 17–25 kg (37–54 lb) for normal-weight, 14–23 kg (31–50 lb) for overweight, and 11–19 kg (25–42 lb) for obese women.

Gaining outside the recommended range increases risks like gestational diabetes, preeclampsia, low birth weight, or preterm birth. It is important to discuss your individual situation with your healthcare provider — these calculators are guidance only.