Pregnancy Weight Gain Calculator

kg
cm

About the Pregnancy Weight Gain Calculator

Gaining an appropriate amount of weight during pregnancy supports healthy foetal development while reducing risks associated with gaining too little or too much.

Formula Used

Pre-Pregnancy BMI = weight(kg) / [height(m)]² (Recommended gain range depends on this BMI category)

How It Works

This calculator uses your pre-pregnancy BMI to determine which Institute of Medicine (IOM) weight gain category you fall into, and shows the recommended total gain range.

Step by Step

  1. Calculate your pre-pregnancy BMI from your weight and height.
  2. Match your BMI to the IOM weight-gain category (underweight, normal, overweight, obese).
  3. Read off the recommended total weight gain range for a single or twin pregnancy.

Worked Example

Example: A woman 60 kg, 160 cm tall (BMI = 23.4, Normal):

Recommended gain = 11.5 - 16 kg for the full pregnancy.

Reference Table

Pre-Pregnancy BMIRecommended Total Gain
Underweight (<18.5)12.5 - 18 kg
Normal (18.5-24.9)11.5 - 16 kg
Overweight (25-29.9)7 - 11.5 kg
Obese (30+)5 - 9 kg

Frequently Asked Questions

Why does BMI affect the recommendation?

Women who start pregnancy underweight are advised to gain more, while those starting at a higher BMI are advised to gain less, to support a healthy outcome.

Is the recommendation different for twins?

Yes, recommended gain is higher for twin pregnancies since more weight supports two babies.

Should I follow this without a doctor's input?

This is a general guideline - always discuss your specific weight gain plan with your doctor or midwife.