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Pregnancy Weight Gain Calculator (by BMI, incl. Twins)

See how much weight to gain during pregnancy from your height and pre-pregnancy weight, for one baby or twins, plus the weekly pace left.

Tool inputs stay in your browser · optional AI search sends your query

Good to know: Scope: the recommended total weight gain for a pregnancy with one baby or twins, based on your body mass index (BMI) before pregnancy, plus an optional check of how much you have gained so far and the average weekly pace left to week 40. Not included: triplets or more (the CDC says to talk with your health care provider), calorie or meal plans, weight-loss advice, and any medical judgment; your provider may set a different goal for you. The ranges are the Institute of Medicine (IOM, now the National Academy of Medicine) 2009 guidelines that the CDC publishes: one baby 28–40 lb (underweight), 25–35 lb (normal weight), 15–25 lb (overweight), 11–20 lb (obese); twins 37–54 lb, 31–50 lb and 25–42 lb (IOM provisional guidelines), and 50–62 lb for underweight with twins, which the CDC takes from a 2003 study because the IOM had too little data. The weekly pace for the 2nd and 3rd trimesters (one baby only) comes from IOM Table S-1, which assumes 1.1–4.4 lb in the first trimester. BMI uses the CDC formula: weight (lb) ÷ height (in)² × 703, rounded to one decimal. Weeks of pregnancy are counted from the first day of your last menstrual period, as on the CDC weight gain trackers. Everything stays in this browser tab; nothing is sent or saved. Independent ToolsKo calculation, not medical advice. Sources reviewed November 12, 2026.

How to use it (step by step)

  1. 1Enter your height and your weight before you got pregnant (or at your first prenatal visit if you do not know it), and pick one baby or twins.
  2. 2Read your BMI group and the recommended total gain for the whole pregnancy.
  3. 3Optional: add your weight today and how many weeks pregnant you are to see how much you have gained and the average weekly pace left to week 40. Bring the numbers to your next prenatal visit.

Words to know

BMI (body mass index)
A number from your weight and height (weight in pounds ÷ height in inches squared × 703). It sorts adults into groups such as normal weight or overweight; it does not measure health on its own.
Gestational weight gain
The weight you gain while pregnant. It includes the baby, placenta, extra blood and fluid, larger breasts and uterus, and some stored fat.
Trimester
One of the three parts of pregnancy, each about three months long. Most of the weight is usually gained in the second and third trimesters.
Weeks pregnant
Counted from the first day of your last menstrual period, not from the day you conceived. The CDC weight gain trackers count this way, up to week 40.

Explore tools for Australia, the US & Europe →

Sources & methods

References checked November 11, 2026. Read each tool’s scope and assumptions before relying on its result.

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