🤰 Pregnancy Weight Gain Calculator
Healthy weight gain range during pregnancy
Written by Albert Mateos · Founder & Editor
Last reviewed: May 2, 2026
How it works
Track healthy weight gain during pregnancy based on IOM guidelines. Enter your pre-pregnancy weight, height, and current week of gestation. Get your recommended total weight gain range and see if you're on track. Personalized by pre-pregnancy BMI category.
How to Use This Calculator
- Enter your pre-pregnancy weight and height.
- Enter your current week of pregnancy.
- Select if you're carrying a single baby or multiples.
- Review the recommended weight gain range based on IOM guidelines.
Example
Inputs: Pre-pregnancy BMI 22, week 20, single pregnancy
Result: Recommended gain so far: 5-7 kg; total target: 11.5-16 kg
What it means: At week 20 with a healthy starting BMI, you should have gained 5-7 kg. Full-term target is 11.5-16 kg total.
Tips
- Underweight women (BMI <18.5) should aim for higher total gain (12.5-18 kg).
- Overweight women (BMI 25-30) should target less (7-11.5 kg).
- Most weight gain happens in trimesters 2 and 3 — trimester 1 is usually 0.5-2 kg.
- Rapid gain (>1 kg/week) in late pregnancy can indicate preeclampsia — notify your provider.
Frequently Asked Questions
- What if I'm gaining more or less than recommended?
- Small deviations are normal. Weight gain isn't linear — some weeks you'll gain more, others less. Consistently gaining well above or below the range may warrant a conversation with your healthcare provider. The guidelines are ranges, not strict targets.
- When does most pregnancy weight gain happen?
- Most weight gain occurs in the second and third trimesters. In the first trimester, 1-2 kg total is typical. After that, expect roughly 0.5 kg/week for normal-weight women. The rate varies by pre-pregnancy BMI.
Authoritative resources
We recommend these external sources for further reading from recognized health organizations and peer-reviewed literature:
- Weight Gain During Pregnancy: IOM Guidelines — NIH / IOM
- Pregnancy weight gain — ACOG — ACOG
Scientific References
This calculator is based on peer-reviewed research and established health guidelines:
- Institute of Medicine (IOM). Weight Gain During Pregnancy: Reexamining the Guidelines. National Academies Press. 2009.