Free pregnancy tool
Pregnancy weight gain calculator
Enter your height and your weight before pregnancy to see your BMI, the recommended total weight gain for one baby or twins, and a simple week-by-week chart.
Your BMI and recommended weight gain will appear here.
Recommended total gain
Week-by-week pathway
Cumulative gain in kg by week. A guide only: the line starts with a small first-trimester gain, then follows the average weekly rate for your category. Real pregnancies vary.
Estimates only. This tool gives a general estimate based on the information you enter. It is not a diagnosis or medical advice. Please consult your doctor to confirm dates and for personal guidance. Nothing you enter is sent anywhere: the calculation runs in your browser.
How the recommended range is chosen
The ranges here come from the 2009 guidance of the US Institute of Medicine (now the National Academy of Medicine). They depend on your body mass index (BMI) before pregnancy: your weight in kilograms divided by your height in metres squared.
- Underweight (BMI under 18.5): 12.5 to 18 kg
- Normal (18.5 to 24.9): 11.5 to 16 kg
- Overweight (25 to 29.9): 7 to 11.5 kg
- Obesity (30 or more): 5 to 9 kg
For twins, the IOM gives provisional ranges: 17 to 25 kg (normal), 14 to 23 kg (overweight) and 11 to 19 kg (obesity). They are based on limited data and are not set for underweight women.
A note on Asian BMI cut-offs
Some Indian and Asian guidelines use lower BMI cut-offs because health risks such as diabetes can appear at lower BMI in Asian populations. A 2004 WHO expert consultation reported this and suggested extra public-health action points at BMI 23 and 27.5, while keeping the standard WHO cut-offs as international classifications. We could not find official weight-gain ranges for pregnancy matched to those Asian cut-offs, and the ICMR announced in 2025 that it is studying gestational weight gain in Indian women to build India-specific guidance. For that reason this calculator uses the standard categories only. If you are in an Asian BMI risk group, your doctor may adjust your target.
What to do with the result
Weigh yourself at antenatal visits and share the numbers with your doctor. Eating well matters more than eating for two: read our guide to foods to eat during pregnancy, and see what is checked at each visit. Sudden swelling of the face or hands, or very rapid weight gain, should be reported to your doctor.
Talk to a doctor
A calculator cannot replace a check-up. Our team can confirm your dates and plan your care.
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Frequently asked questions
How much weight should I gain during pregnancy?
It depends on your weight before pregnancy. Under the widely used US Institute of Medicine (IOM) 2009 guidance, women with a normal BMI are advised to gain 11.5 to 16 kg with one baby. Women who start underweight are advised more (12.5 to 18 kg), and women who start overweight or with obesity are advised less (7 to 11.5 kg and 5 to 9 kg).
How much should I gain with twins?
The IOM gives provisional ranges for twins: 17 to 25 kg for a normal pre-pregnancy BMI, 14 to 23 kg for overweight and 11 to 19 kg for obesity. It gives no range for underweight women with twins, so your doctor will advise you. Weekly rates are not defined for twins either.
Do these ranges apply to Indian women?
The IOM ranges come from studies of mostly Western populations. The WHO has noted that Asian populations can carry health risks at lower BMI values, and the Indian Council of Medical Research announced in 2025 a national study to build India-specific gestational weight gain guidance. Until then, doctors in India commonly use the IOM ranges as a reference. This calculator uses the standard BMI categories, and your doctor may judge your own target differently.
What if I am gaining more or less than the range?
The range is a general guide, not a pass or fail mark. Gaining faster or slower than expected is a reason to talk to your doctor at your next antenatal visit. Do not try to diet to lose weight in pregnancy unless your doctor tells you to.
How much do I gain in the first trimester?
The IOM guidance assumes a small gain of about 0.5 to 2 kg in the first three months, then a steadier weekly gain in the second and third trimesters. The chart on this page follows that pattern.
Is my information saved or sent anywhere?
No. The calculation runs entirely in your browser and nothing you enter leaves your device.
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