Pregnancy Weight Gain Calculator
Recommended total weight gain for your pregnancy, based on your body mass index before pregnancy. The ranges are the Institute of Medicine's, as published by the CDC, for one baby or for twins.
Recommended total gain
25 lb to 35 lb
Pre-pregnancy BMI 23.3, which the guidance groups as normal weight, carrying one baby.
Extra daily calories, per the same guidance: none in the first trimester, about 340 in the second and about 450 in the third.
All ranges for one baby
How the ranges work
The recommendation is not one number for everyone. It starts from your body mass index before pregnancy, and it moves in the direction people often find counterintuitive: the lower your starting BMI, the more weight the guidance expects you to gain.
That is why the tool shows all four bands rather than only yours. A range is not a score, and someone whose recommended gain is 11 to 20 pounds is not being told to do better than someone at 28 to 40. They started from a different place.
The calorie side is smaller than most people assume. First trimester generally needs no extra calories at all, and the additions in the second and third trimesters, about 340 and 450 a day, are roughly a substantial snack rather than a second dinner.
A note on what these numbers describe: a whole pregnancy. A reading in a single week says very little on its own, which is why this tool gives the range and stops there instead of grading a number you type in.
Where you are being cared for matters
These are United States figures. The Institute of Medicine ranges are used well beyond the US and are the most widely cited anywhere, but they are not a global standard in the way the WHO growth charts for babies are.
Two things vary by country. Some publish their own gestational weight gain guidance with different ranges. And the BMI categories underneath the ranges are themselves debated for some populations: the WHO recognises different BMI action points for Asian populations than the 25 and 30 thresholds used here.
We have not built a country switcher for this, and the reason is worth stating. Pairing one country's weight-gain ranges with another country's BMI cut-points is not an established practice, and a dropdown would imply a combination that no guideline body has published. If you are being cared for outside the US, the numbers your own provider uses are the right ones.
For your baby after birth, the picture is different and genuinely international: the WHO growth charts are the reference recommended in most countries for children under two, and our percentile calculator uses them directly.
Frequently asked questions
How much weight should I gain during pregnancy?
It depends on your body mass index before pregnancy. For one baby the Institute of Medicine ranges, as published by the CDC, are 28 to 40 pounds if you were underweight, 25 to 35 at a normal weight, 15 to 25 if overweight and 11 to 20 if obese. Twins have their own, higher ranges.
How much weight should I gain with twins?
More, and the ranges are wider: 37 to 54 pounds at a normal pre-pregnancy BMI, 31 to 50 if overweight and 25 to 42 if obese. The CDC notes that the underweight-with-twins figure of 50 to 62 pounds is the one row not drawn from the Institute of Medicine.
How many extra calories do I need?
Fewer than most people expect early on. The CDC's guidance is that the first trimester generally needs no extra calories, the second about 340 more a day and the third about 450 more.
What if I am gaining more or less than the range?
It is common: a study cited by the CDC found only about one in three women gained within the recommended amount. The ranges describe a whole pregnancy rather than any single week, so this is a conversation for your prenatal visits rather than something to judge from one reading at home.
Do these ranges apply everywhere?
They are United States guidance. The Institute of Medicine ranges are widely used internationally, but several countries publish their own, and the BMI categories themselves are debated for some populations, with WHO recognising different action points for Asian populations. If your care is outside the US, your own provider's numbers are the ones to use.
Does this calculator tell me if my gain is healthy?
No, and deliberately. It gives you the published range for your starting point. Whether a particular pattern of gain is fine is a clinical judgement that needs your history and your measurements over time, which is what prenatal appointments are for.
From the bump to the first three years
Growbaby picks up where this leaves off: soothing that reacts to crying, sleep routines for your baby's exact age, and a growth journal that keeps every measurement in one place.
This tool is for general informational purposes only. It is not a medical device and does not provide medical advice, diagnosis or treatment. For any question about your or your baby's health, always consult a qualified healthcare provider.