Pregnancy Weight Gain Calculator
Estimate a healthy pregnancy weight-gain range based on your pre-pregnancy BMI and current week, using IOM guidelines.
Reviewed October 7, 2026 Runs in your browser — inputs are never stored
This tool provides general educational estimates only and is not medical advice. It does not diagnose, treat, or replace guidance from a qualified healthcare provider. Consult a doctor for decisions about your health.
About the Pregnancy Weight Gain Calculator
The pregnancy weight gain calculator shows the recommended total weight gain during pregnancy based on your pre-pregnancy BMI, using the U.S. Institute of Medicine (now National Academy of Medicine) guidelines. It calculates your BMI from pre-pregnancy weight and height, places you in a BMI category and shows the recommended range, adjusted for twins if needed. It also estimates where your gain should be for your current week. Recommended gain is lower for higher pre-pregnancy BMI because extra gain raises the risk of complications. Discuss your own targets with your midwife or doctor.
How to use it
- 1Enter your weight before pregnancy.
- 2Enter your height.
- 3Enter your current week of pregnancy.
- 4Choose whether you are expecting twins.
- 5Press Calculate to see your recommended total gain and the range for your current week.
Worked example
a woman who weighed 62 kg before pregnancy and is 165 cm tall has a pre-pregnancy BMI of about 22.8, in the normal range. The recommended total gain for a single baby is 11.5–16 kg.
How it works
IOM ranges (singleton)
- Underweight: 12.5–18 kg
- Normal: 11.5–16 kg
- Overweight: 7–11.5 kg
- Obese: 5–9 kg
Who it is for
Expectant parents tracking pregnancy weight gain.
Why it helps
It provides an evidence-based target range tailored to your starting BMI.
Common use cases
- Checking whether weight gain is on track at a given week
- Understanding how recommendations differ by starting BMI
- Preparing questions for a prenatal appointment
Frequently asked questions
A:It depends on your starting BMI; most healthy-weight women gain 11.5–16 kg.
A:Yes, recommended gain is higher for multiple pregnancies.
Reviewed for accuracy · Last updated October 7, 2026
Formulas follow recognised clinical references — including WHO BMI classifications, the Mifflin-St Jeor equation, and Naegele’s rule — and are periodically checked against published reference values.
CalcWisee Editorial Team
Calculator development and formula review
CalcWisee is an independent site founded by Ayman. Every calculator is built from a published formula or official definition, tested against hand-worked examples before it goes live, and corrected promptly when a reader reports an issue to ayman@calcwisee.com.
Expertise: Financial mathematics, Health and fitness formulas, Applied mathematics, Unit conversion standards
References & sources
Related guides
Understanding BMI and a Healthy Weight Range
Learn how BMI is calculated, what each category means, a worked example, and the real limits of BMI as a health measure.
BMI Calculator: Check If Your Weight Is Healthy
Your weight alone does not tell the whole story. Use the CalcWisee BMI Calculator to calculate your Body Mass Index, find your weight category, and understand what it means for your health.
BMR Calculator: Calculate Your Daily Calorie Needs
Understand how many calories your body burns at rest and estimate your daily calorie needs with the free CalcWisee BMR Calculator — using the Mifflin–St Jeor Equation.