Healthy weight gain, week by week
Based on your pre-pregnancy BMI and IOM guidelines.
Results update as you type 🥑
How much to gain, and when
Recommended pregnancy weight gain depends mostly on your pre-pregnancy BMI. We classify it, then apply Institute of Medicine (IOM) ranges: less if you started heavier, more if you started lighter.
Gain is slow in the first trimester (about 0.5–2 kg total), then steadier — roughly 0.4–0.5 kg per week in the second and third trimesters for a normal-BMI pregnancy.
These are population ranges for a singleton pregnancy. Twins, medical conditions and individual circumstances change them — your healthcare provider’s guidance comes first.
Common questions
Why does pre-pregnancy BMI matter?
Starting weight changes the healthy gain range. Higher BMI needs less added weight; lower BMI needs more to support the baby.
Is it bad to gain too much or too little?
Both carry risks for parent and baby. The ranges aim to balance them — discuss your trajectory with your provider.
Does this work for twins?
No — multiples have higher recommended gain. This tool is for a single baby; ask your provider for multiples.
Is my data stored?
No. Everything is calculated in your browser. Nothing is sent to a server or saved.
Sources & references
- Mifflin MD, St Jeor ST, et al. “A new predictive equation for resting energy expenditure in healthy individuals.” Am J Clin Nutr. 1990;51(2):241–247.
- Frankenfield D, Roth-Yousey L, Compher C. “Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults.” J Am Diet Assoc. 2005;105(5):775–789.
This calculator provides estimates for general educational use and is not medical advice. Consult a qualified professional before making significant dietary changes.