Free tool
Pregnancy weight gain calculator
Enter your height, pre-pregnancy weight, current weight and how many weeks pregnant you are, in metric or imperial units. The tool calculates your pre-pregnancy BMI, the IOM recommended total weight gain range for that category, and a rough sense of whether your gain so far is tracking below, on, or above the typical pace. Nothing you type is stored or sent anywhere.
Your result
Recommended total weight gain for a full-term singleton pregnancy: 0 to 0 kg.
Typical gain by this week for your BMI category is about 0 to 0 kg.
This is a general estimate from a standard formula (IOM guidelines), not medical advice and not a diagnosis. It assumes a single baby and does not account for medical conditions, multiples, or your own doctor’s assessment at your antenatal check-ups. Consult your doctor about your weight gain and any concerns.
IOM recommended weight gain by pre-pregnancy BMI
Figures are for a single baby (singleton) pregnancy over the full term. Most of this gain happens after the first trimester, when total gain is usually about 0.5 to 2 kg regardless of BMI category.
| Pre-pregnancy BMI category | Total recommended gain | 2nd/3rd trimester rate |
|---|---|---|
| Underweight (below 18.5) | 12.5 to 18 kg | About 0.44 to 0.58 kg/week |
| Normal (18.5 to 24.9) | 11.5 to 16 kg | About 0.35 to 0.50 kg/week |
| Overweight (25 to 29.9) | 7 to 11.5 kg | About 0.23 to 0.33 kg/week |
| Obese (30 and above) | 5 to 9 kg | About 0.17 to 0.27 kg/week |
Questions
How is the pregnancy weight gain range calculated?
This tool uses the IOM (Institute of Medicine, now the US National Academy of Medicine) 2009 pregnancy weight gain guidelines, a widely used reference range internationally including among doctors in India. It first works out your pre-pregnancy BMI from your height and pre-pregnancy weight, then looks up the total weight gain range recommended for that BMI category over a full singleton pregnancy.
What are the IOM recommended weight gain ranges by BMI category?
For a singleton pregnancy: underweight (BMI below 18.5) is 12.5 to 18 kg, normal weight (18.5 to 24.9) is 11.5 to 16 kg, overweight (25 to 29.9) is 7 to 11.5 kg, and obese (30 and above) is 5 to 9 kg. Most of this gain happens after the first trimester.
Does gaining outside this range always mean something is wrong?
No. The range is a general guideline, not a strict cutoff. Gain can vary week to week, especially with nausea early on or a growth spurt later, and the “typical pace” estimate here is a rough band, not a clinical assessment. If your gain looks well outside the range, or you are worried, raise it with your doctor at your next antenatal visit rather than relying on this tool.
Does this calculator apply to twin or multiple pregnancies?
No. This tool assumes a single baby (singleton) pregnancy. Twin and multiple pregnancies have their own, higher recommended weight gain ranges. It also does not account for medical conditions such as gestational diabetes, thyroid disorders or pre-eclampsia. This is a general estimate from a standard formula, not medical advice, and it does not diagnose anything: your doctor’s reading of your antenatal check-ups takes priority.
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