How to use the Pregnancy Weight Gain Calculator
This tool shows the recommended weight gain in pregnancy based on pre-pregnancy BMI, using the Institute of Medicine ranges.
Open the Pregnancy Weight Gain Calculator →
What you need to enter
- Height (cm)
- Pre-pregnancy weight (kg)
- Twins?
The formula
BMI = weight ÷ height². Recommended total gain: underweight 12.5–18 kg, normal 11.5–16 kg, overweight 7–11.5 kg, obese 5–9 kg (single baby).
Worked example
Using the default values in the calculator:
- Height (cm): 165
- Pre-pregnancy weight (kg): 62
- Twins?: Single baby
| Pre-pregnancy BMI | 22.8 |
| Recommended total gain | 11.5 – 16 kg |
Tips for better results
- Discuss targets with your midwife or doctor.
- Gain is not even across trimesters.
Common mistakes to avoid
- Dieting in pregnancy.
- Comparing with another person.
Please note: Health calculators and guides give general estimates, not medical advice. Talk to a doctor or other qualified professional about your own health. See our Disclaimer.