Your pre-pregnancy BMI
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⚖️ Pregnancy tool
Weight Gain Calculator
See your recommended pregnancy weight-gain range based on your pre-pregnancy BMI and how far along you are, using Institute of Medicine guidelines.
Recommended gain by week —
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BMI category
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Total recommended gain
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Typical weekly gain now
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Based on Institute of Medicine ranges. Singleton pregnancy. Carrying twins, or specific health conditions, change these numbers — always follow your provider’s personal guidance.
Remember: This is an estimate, not medical advice. Dates and figures are general guidance — every pregnancy is different. Your healthcare provider’s assessment, especially from an early ultrasound, always takes priority. Always speak with your provider about your pregnancy.
Common questions
How much weight should I gain in pregnancy?
It depends on your pre-pregnancy BMI. The Institute of Medicine suggests about 12.5–18 kg if you were underweight, 11.5–16 kg at a healthy weight, 7–11.5 kg if overweight, and 5–9 kg if obese — for a single baby.
Where does the weight go?
Only a portion is the baby (around 3–3.5 kg). The rest is the placenta, amniotic fluid, extra blood and fluid, larger breasts and uterus, and some fat stores to support breastfeeding.
I’m gaining faster or slower than the range — is that ok?
Gain isn’t perfectly steady, and one reading rarely matters. Patterns over time are what your provider watches. Bring any concerns to your appointments rather than worrying week to week.
Does this apply to twins?
No — twin and higher-order pregnancies have different, higher recommended ranges. This calculator is for a single baby. Your provider will guide you if you’re carrying multiples.