Use this free online pregnancy weight gain calculator to find your pre-pregnancy BMI and the recommended total weight gain range for a healthy pregnancy. Just enter your pre-pregnancy height and weight to get an instant, guideline-based estimate. This tool offers general information only and is not a substitute for advice from your doctor or midwife.
General guideline — consult your doctor for personalized advice.
How to Use the Pregnancy Weight Gain Calculator
Enter your pre-pregnancy height in centimeters in the "Pre-Pregnancy Height (cm)" field.
Enter your pre-pregnancy weight in kilograms in the "Pre-Pregnancy Weight (kg)" field.
Click "Calculate Weight Gain" to see your results.
Review your pre-pregnancy BMI, BMI category, and recommended total weight gain range in the result box.
Frequently Asked Questions
BMI is calculated using the standard formula: weight in kilograms divided by the square of your height in meters (weight (kg) ÷ height (m)²), based on the height and weight you enter before pregnancy.
Once your BMI is calculated, it's matched to a category: Underweight (below 18.5) suggests 12.5-18 kg, Normal weight (18.5-24.9) suggests 11.5-16 kg, Overweight (25-29.9) suggests 7-11.5 kg, and Obese (30 or above) suggests 5-9 kg of total pregnancy weight gain.
The calculator will show an error message asking you to enter a valid pre-pregnancy height and weight, since both values must be greater than zero to produce a result.
Yes, it's completely free with no sign-up required. That said, it only gives general, educational guidance based on standard BMI ranges — always consult your doctor or midwife for advice tailored to your pregnancy, especially for twins or other special circumstances.