Check your pre-pregnancy BMI against Institute of Medicine ranges for weight gain and weekly pace in the second and third trimesters, singleton or twin.
BMI and the range lookup run entirely in your browser. Your weight and height never leave your device.
Screening estimate based on population ranges — not medical advice. Your provider owns the target.
The calculator classifies your pre-pregnancy BMI (weight ÷ height², computed in metric units) and looks up the Institute of Medicine (2009) pregnancy weight-gain ranges that correspond to that category. It is a screening aid: the decision about your target stays with your clinician.
Theirs, without question. The Institute of Medicine ranges shown here are population-level starting points; your clinician sees your height, history, labs and pregnancy in front of them and may set a genuinely different goal for you. Use this page to understand the general shape of recommended gain, and bring the discussion — not the number — to your appointments.
Not in the literal sense. Energy needs rise only modestly: roughly no extra calories in the first trimester, then about +340 kcal per day in the second and +450 in the third — a snack, not a double portion. The quality of what you eat matters far more than the quantity, and micronutrient needs (iron, folate, calcium) climb well before calorie needs do.
The evidence behind the ranges compares outcomes across groups: people who start at a higher BMI do best with a narrower gain (5–9 kg for obesity), because excess gain adds gestational-diabetes and delivery complications on top of an already-elevated baseline, while lower-BMI starts need more gain to support fetal growth. The range is a balance struck at the population level, not a moral grade.
One weigh-in outside the band is not a verdict. Rate of gain over the second half of pregnancy predicts outcomes better than any single number, and short-term wobbles (fluid, measurement timing) are normal. Mention it at your next prenatal visit rather than changing your diet on your own — and treat twin or higher-order pregnancies as clinician-managed territory.
No. BMI and the range lookup are plain arithmetic running entirely in your browser. Your weight, height and results are never transmitted, stored or logged — they exist only on your device while the page is open.
If you just finished with Weight Gain in Pregnancy, the natural next steps are Age Calculator, Calorie Calculator, Body Fat Calculator, or browse every tool in Health Tools.