Free pregnancy weight gain calculator. Find out exactly how much weight you should gain during pregnancy based on your pre-pregnancy BMI and current week. Get trimester by trimester targets and track your progress throughout your pregnancy journey.
How to Use This Pregnancy Weight Gain Calculator
Enter your pre-pregnancy weight and height. Drag the slider to your current week of pregnancy. If you are expecting twins tap the Twins button. Optionally enter your current weight to track your progress. Then click Calculate My Weight Gain.
What This Calculator Shows You
This calculator shows your recommended total weight gain range for your entire pregnancy, your pre-pregnancy BMI and category, a breakdown of how much to gain in each trimester, your recommended weekly weight gain rate for the second and third trimester, how many weeks are remaining, and if you enter your current weight it tells you whether you are on track above or below the expected gain for your current week.
How Much Weight Should I Gain During Pregnancy
The amount of weight you should gain during pregnancy depends on your pre-pregnancy BMI. If you were underweight before pregnancy with a BMI below 18.5 the recommended total gain is 12.5 to 18 kilograms. If you were a normal weight with a BMI between 18.5 and 24.9 the recommended gain is 11.5 to 16 kilograms. If you were overweight with a BMI between 25 and 29.9 the recommended gain is 7 to 11.5 kilograms. If you were in the obese range with a BMI of 30 or above the recommended gain is 5 to 9 kilograms.
How Much Weight to Gain in Each Trimester
During the first trimester most women gain between 0.5 and 2 kilograms as the baby is still very small. During the second trimester weight gain becomes more consistent at approximately 0.3 to 0.5 kilograms per week depending on your pre-pregnancy BMI. The third trimester follows a similar rate to the second trimester as your baby gains the most weight in the final weeks before birth.
Weight Gain During Twin Pregnancy
If you are expecting twins you should expect to gain more weight than with a single pregnancy. The recommended range for twins is 16.8 to 24.5 kilograms for women who were a normal weight before pregnancy. The guidelines are slightly different based on your pre-pregnancy BMI. Always discuss your individual targets with your healthcare provider when pregnant with multiples.
Where Does Pregnancy Weight Gain Come From
Many women wonder why they need to gain so much weight during pregnancy. The weight is distributed across many parts of your body including your baby who accounts for approximately 3 to 4 kilograms, the placenta at around 0.7 kilograms, amniotic fluid at around 0.8 kilograms, increased breast tissue at around 0.9 kilograms, increased blood volume at around 1.8 kilograms, fluid in body tissues at around 1.8 kilograms, and stored fat for breastfeeding at around 2.7 kilograms.
Is It Safe to Diet During Pregnancy
No. You should never try to lose weight during pregnancy. Gaining too little weight can affect your baby’s growth and development. If you are concerned about gaining too much weight focus on eating nutrient dense foods and staying active with pregnancy safe exercise rather than restricting calories. Always speak with your doctor or midwife before making any changes to your diet during pregnancy.
Frequently Asked Questions
How accurate is this pregnancy weight gain calculator?
This calculator uses guidelines from the Institute of Medicine which are the internationally recognized standards for pregnancy weight gain. The results are estimates based on your pre-pregnancy BMI. Your individual targets may differ based on your medical history so always confirm your goals with your healthcare provider.
What if I am gaining weight too fast?
If you are gaining weight faster than recommended do not try to diet. Instead speak with your midwife or doctor. They may suggest choosing more nutrient dense lower calorie foods and increasing gentle activity like walking.
What if I am not gaining enough weight during pregnancy?
If you are gaining weight too slowly speak with your healthcare provider immediately. You may need to increase your calorie intake with nutritious foods like nuts, avocado, dairy, lean proteins and whole grains.
Does morning sickness affect weight gain in the first trimester?
Yes. Many women lose weight or gain very little in the first trimester due to morning sickness and nausea. This is normal for most women. Your healthcare provider will monitor your overall gain throughout the pregnancy.
Is this calculator suitable for high risk pregnancies?
This calculator provides general guidelines based on IOM recommendations. If you have a high risk pregnancy, gestational diabetes, pre-eclampsia or any other medical condition your weight gain targets should be determined by your healthcare provider.
Is this pregnancy weight gain calculator free?
Completely free. No sign up, no login, no limits.
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Last updated: March 2026 · Free tool by AllTheTools.com