Pregnancy Weight Gain Calculator
See your recommended pregnancy weight gain by pre-pregnancy BMI (IOM guidelines), with a healthy target for your current week.
Updated October 2026
Ranges follow the US Institute of Medicine (2009) guidelines, which base healthy pregnancy weight gain on your pre-pregnancy BMI. Most of the gain comes in the second and third trimesters; the first trimester adds only a little. Twin ranges are provisional. This is general information, not medical advice — your own target can differ, so follow the plan your doctor or midwife sets for you.
This is an estimate for general information only and is not medical advice. Talk to a healthcare professional for decisions about your health.
TThe Crypto Tools69+ free crypto calculators — profit, fees, DCA and more.Our networkVisit →How much weight should you gain during pregnancy? It depends mostly on your weight before you were pregnant. This calculator uses your pre-pregnancy BMI and the US Institute of Medicine (IOM) guidelines to show your recommended total gain — and how much is healthy by any given week.
Enter your height and pre-pregnancy weight, your current week, and optionally your current weight to see whether you're tracking within the recommended range. It covers both a single baby and twins.
How to use it
- 1Pick your units and whether you're carrying one baby or twins.
- 2Enter your height and your weight before pregnancy — these set your pre-pregnancy BMI category.
- 3Enter your current week of pregnancy (1–42).
- 4Optionally add your current weight to see your gain so far and whether it's on track.
Frequently asked questions
How much weight should I gain during pregnancy?+
For a single baby, the IOM recommends total gain by pre-pregnancy BMI: underweight (BMI under 18.5) 28–40 lb, normal (18.5–24.9) 25–35 lb, overweight (25–29.9) 15–25 lb, and obese (30+) 11–20 lb. Twins have higher ranges. The calculator picks the right range from your BMI.
How is the weekly recommendation worked out?+
Gain is slow in the first trimester — only about 1–4.5 lb total — then steadier in the second and third. The IOM gives weekly rates by BMI category (for example about 1 lb/week for a normal-weight woman), which this adds on top of the first-trimester gain to estimate how much is healthy by your current week.
What if I'm above or below the range?+
The range is a guide, not a hard rule, and one reading doesn't decide anything. Both gaining too little and too much carry some risk, so if your gain is consistently outside the range, talk it through with your doctor or midwife rather than changing your diet drastically on your own.
Does the weight come off after birth?+
Some is lost at delivery (the baby, placenta and fluid — often 10–13 lb), and the rest typically comes off gradually over the following months, especially with breastfeeding and normal activity. How quickly varies a lot from person to person.
Is this medical advice?+
No. It's general information based on population guidelines. Your own healthy target can differ based on your health, your pregnancy and your provider's judgment — always follow the plan your doctor or midwife gives you.
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