Pregnancy Weight Gain Calculator

How to Use This Calculator

This calculator helps you track healthy weight gain throughout your pregnancy based on your pre-pregnancy BMI and current gestational week. Follow these steps:

1. Select your unit system -- choose between Imperial (pounds and inches) or Metric (kilograms and centimeters) depending on your preference.
2. Enter your pre-pregnancy weight -- input the weight you were at before becoming pregnant. This establishes your baseline BMI category.
3. Enter your height -- provide your height so the calculator can determine your Body Mass Index.
4. Enter your current weight -- input your most recent weight measurement to see how your gain compares to recommendations.
5. Enter your gestational week -- specify your current week of pregnancy (1 to 42) to receive week-specific guidance.
6. Indicate if it is a multiple pregnancy -- check the box if you are carrying twins or more, as weight gain recommendations differ significantly.
7. Review your results -- the right panel displays your BMI category, current status, recommended gain ranges, trimester breakdown, and detailed guidelines.

Understanding Healthy Weight Gain During Pregnancy

Why Does Pregnancy Weight Gain Matter?

Gaining the right amount of weight during pregnancy supports your baby's healthy development and helps protect your own well-being. Too little weight gain can increase the risk of preterm birth and low birth weight, while excessive gain is associated with gestational diabetes, preeclampsia, cesarean delivery, and difficulty losing weight postpartum. The optimal range depends on your pre-pregnancy Body Mass Index, which is why individualized guidelines are essential.

Weight Gain by Trimester

Weight gain is not distributed evenly across pregnancy. During the first trimester (weeks 1 through 12), most women gain only 1 to 4 pounds total, as the baby is very small and morning sickness may limit appetite. The second trimester (weeks 13 through 27) is when gain typically accelerates, with most women gaining about 1 to 2 pounds per week. The third trimester (weeks 28 through 40) continues at a similar rate, though some slowing is common in the final weeks before delivery.

Where Does the Weight Go?

Nutrition Tips for Healthy Gain

Focus on nutrient-dense foods rather than simply eating more. Prioritize lean proteins, whole grains, fruits, vegetables, and healthy fats. Most women need an additional 340 calories per day during the second trimester and 450 extra calories per day during the third trimester. Take prenatal vitamins that include folic acid, iron, calcium, and DHA as recommended by your healthcare provider. Stay well-hydrated with water and limit processed foods, sugary beverages, and excessive sodium.

IOM Recommended Weight Gain by Pre-Pregnancy BMI

The Institute of Medicine (IOM) guidelines below represent the recommended total weight gain ranges for singleton and twin pregnancies based on pre-pregnancy BMI category.

Caloric and Nutrient Needs by Trimester

Your caloric requirements increase progressively throughout pregnancy. The table below shows recommended daily caloric intake above your normal needs, along with key nutrient targets based on ACOG (American College of Obstetricians and Gynecologists) guidelines.

Safe Exercise During Pregnancy

ACOG recommends at least 150 minutes of moderate-intensity aerobic activity per week for pregnant women with no complications. Regular exercise during pregnancy helps manage weight gain, reduces the risk of gestational diabetes and preeclampsia, improves mood, and can lead to shorter labor.