How much weight should I gain in pregnancy?

It depends on your pre-pregnancy BMI. IOM guidelines suggest 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.

How is the healthy range calculated?

The calculator works out your pre-pregnancy BMI from your weight and height, matches it to the IOM category, and then estimates how much of that total gain is typical by your current week.

Is it normal to gain little weight in the first trimester?

Yes. Most weight gain happens in the second and third trimesters. In the first trimester many people gain only 0.5–2 kg in total, and some lose a little due to nausea.

Does this apply to twins?

No. Recommended weight gain for twins is higher. This calculator is for a single baby. Always follow your own doctor's guidance.

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Pregnancy Weight Gain Calculator ⚖️

See a healthy weight gain range for your body and your stage of pregnancy.

Based on Institute of Medicine (IOM) guidelines for a single baby. Twins and individual health needs differ. Every pregnancy is unique — always follow your own doctor’s advice. This tool is not medical advice.

How much weight gain is healthy?

Healthy pregnancy weight gain depends on your weight before pregnancy. The Institute of Medicine (IOM) sets recommended ranges by pre-pregnancy BMI. Gaining within your range supports your baby’s growth while keeping risks lower for both of you.

Most gain happens after the first trimester — often around 0.3–0.5 kg per week in the second and third trimesters for someone who started at a healthy weight. Remember that weight gain is just one part of a healthy pregnancy.

Keep tracking

You can log your weight and your baby’s growth in your Parent Vibes dashboard, and follow what’s happening each week in our pregnancy guide.

Weight gain calculator FAQs

How much weight should I gain in pregnancy?: It depends on your pre-pregnancy BMI. IOM guidelines suggest 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.
How is the healthy range calculated?: The calculator works out your pre-pregnancy BMI from your weight and height, matches it to the IOM category, and then estimates how much of that total gain is typical by your current week.
Is it normal to gain little weight in the first trimester?: Yes. Most weight gain happens in the second and third trimesters. In the first trimester many people gain only 0.5–2 kg in total, and some lose a little due to nausea.
Does this apply to twins?: No. Recommended weight gain for twins is higher. This calculator is for a single baby. Always follow your own doctor's guidance.