Pregnancy Weight Gain Calculator

Free Pregnancy Weight Gain Calculator

This free pregnancy weight gain calculator estimates a recommended total weight gain range and an expected range for your current week, based on your pre-pregnancy BMI, following published Institute of Medicine (IOM) guidelines. It works for both singleton and twin pregnancies.

Recommended weight gain varies by your starting BMI category — underweight, normal weight, overweight, or obese — because health outcomes for both parent and baby are linked to gaining within an appropriate range. The calculator estimates a modest first-trimester gain, then a steady weekly pace through the second and third trimesters, so you can see where you stand at any point in your pregnancy.

How to Use the Pregnancy Weight Gain Calculator

• Choose Imperial or Metric units.
• Enter your height, pre-pregnancy weight, and current weight.
• Enter your current week of pregnancy and select singleton or twins.
• Click Calculate Weight Gain.
• View your BMI, recommended total range, expected range for this week, and suggested pace ahead.

Features

• Supports both Imperial and Metric units.
• Covers singleton and twin pregnancies.
• Based on published IOM weight gain guidelines.
• Mobile-friendly with print, share, copy, and download options.

Frequently Asked Questions

How much weight should I gain during pregnancy?

It depends on your pre-pregnancy BMI. General guidelines suggest 28 to 40 lb for underweight, 25 to 35 lb for normal weight, 15 to 25 lb for overweight, and 11 to 20 lb for obese individuals carrying a single baby. Twin pregnancies have higher ranges.

Why does recommended weight gain depend on BMI?

Research has linked weight gain within the recommended range for your starting BMI to better outcomes for both parent and baby, while gaining too little or too much is associated with increased risks. This is why guidelines are tailored by BMI category rather than a single number for everyone.

Is it normal to gain weight unevenly throughout pregnancy?

Yes. Many people gain very little, or even lose a small amount, in the first trimester, then gain more steadily through the second and third trimesters. This calculator accounts for that pattern rather than assuming a flat weekly rate throughout.

Should I use this calculator instead of my doctor's advice?

No. This calculator gives a general estimate based on published guidelines. Your OB-GYN or midwife can account for your specific health history, and their guidance should always take priority over a general online tool.

Method and Sources

This calculator works out your pre-pregnancy body mass index (BMI) from your height and weight, places it in one of four categories (underweight, normal weight, overweight, or obese), and shows the total weight-gain range recommended for that category in the 2009 Institute of Medicine guidelines, which are also used by the CDC. The week-by-week range assumes a small gain in the first trimester and a steady pace afterward.

These are population guidelines, not a personal target. Your doctor or midwife may recommend a different range based on your health and pregnancy.

Sources:

• Institute of Medicine (2009) — Weight Gain During Pregnancy: Reexamining the Guidelines
• Centers for Disease Control and Prevention (CDC) — Weight Gain During Pregnancy

This calculator is for general information only and is not medical advice. Read our Calculation Methodology and medical disclaimer.

Related Calculators

Want to know your due date? Try our pregnancy due date calculator. Curious what week and trimester you're in? Check the pregnancy week calculator or the pregnancy trimester calculator. Once your baby arrives, track their weight gain with our baby growth calculator.