Pregnancy Weight Gain Calculator

The range comes from your BMI before pregnancy

Recommendations published by the CDC, following the Institute of Medicine guidelines, set total gain by pre-pregnancy body mass index: 28–40 lb if you were underweight, 25–35 lb at a normal BMI, 15–25 lb if overweight and 11–20 lb with a BMI of 30 or above. Twins carry their own, much larger ranges. Nothing in the recommendation depends on your weight today, which is why the first input is the weight you started at.

How the weekly figure is worked out

The published guidance is a total, not a weekly schedule. The expected range for the week you are in is interpolated here: a first-trimester allowance of roughly 1 to 4 pounds, then the remainder spread evenly across weeks 13 to 40. That is a reasonable reading of the total, and it is an interpolation rather than a published figure — real pregnancies are lumpy, and a single week means very little on its own.

Above or below the range is information, not a verdict

Gaining outside the band is common and is a prompt for a conversation rather than a diagnosis. Nausea in early pregnancy, fluid retention later, a growth scan, twins discovered at a scan, or simply a scale weighed at a different time of day will all move this number. Your midwife or doctor is weighing it against measurements this page cannot see.

Where the weight actually goes

Very little of pregnancy weight is fat. At term the baby accounts for around seven to eight pounds, with the placenta, amniotic fluid, a larger uterus, increased breast tissue, and a blood volume that rises by nearly half accounting for most of the rest. The stored energy reserve is real but modest, and it is what breastfeeding draws on afterwards. This is also why weight loss after birth is not immediate: several pounds of it is fluid that leaves over the following weeks.

Eating for two is the wrong arithmetic

The CDC notes that the first trimester generally requires no extra calories at all, with roughly 340 more per day in the second trimester and about 450 in the third. That is a snack, not a second dinner. Underneath the number, the food quality matters more than the total — folate, iron, iodine and protein carry specific requirements in pregnancy, and a prenatal vitamin exists because diet alone rarely covers folate at the level recommended. Any question about restricting intake during pregnancy belongs with a clinician rather than a calculator.

Frequently Asked Questions