How the pregnancy weight gain chart works
The chart shows the total weight gain, from the start of the pregnancy to the end, that the US Centers for Disease Control and Prevention (CDC) lists for each prepregnancy weight category. There are four categories, set by body mass index (BMI) before pregnancy: underweight (below 18.5), normal weight (18.5 to 24.9), overweight (25.0 to 29.9) and obesity (30.0 to 39.9). Each category has one range for a single baby and one for twins. The calculator works out your BMI, finds your row and highlights it on a chart where every bar uses the same axis, so you can see how the ranges compare.
The category is decided from the unrounded BMI. A BMI that rounds to 25.0 but is really 24.96 is still in the normal weight row. At 200 cm, for example, 74 kg is the first weight in the normal row and 100 kg is the first weight in the overweight row.
Prepregnancy weight versus current weight
The ranges are tied to the weight you had before you were pregnant, not the weight you have now. That is why the first weight box is labelled prepregnancy weight. If you do not know it, use the weight from your first prenatal visit only as a rough stand-in and tell your clinician that is what you did. To see how a BMI is worked out, use the BMI calculator with your weight before pregnancy; do not use your current weight, because pregnancy weight is not a BMI category.
The optional current weight box gives a separate readout: your current weight minus your prepregnancy weight. It is shown on its own and never compared with the range, because the range describes the whole pregnancy and a number from the middle of a pregnancy cannot be judged against it. A negative result is simply shown as a negative change; the page does not label it good or bad. How much you should have gained by a given week is a question for your clinician.
One baby versus twins
With twins the CDC ranges are higher in every row. For a normal weight prepregnancy BMI the single-baby range is 25 to 35 pounds and the twin range is 37 to 54 pounds. For triplets or more, the CDC does not publish a table and advises talking to your healthcare provider, so the calculator shows no numeric range for those pregnancies, and it also shows none when the prepregnancy BMI is 40 or more, because the CDC table used here stops at 39.9.
One row deserves a note. The CDC table says that all of its recommendations come from the Institute of Medicine (IOM) except those for underweight women with twins, which cite Luke and colleagues (2003). The calculator keeps that footnote beside the underweight twin range of 50 to 62 pounds so you can see where it comes from.
Worked example: 165 cm and 60 kg before pregnancy
Take a woman who is 165 cm tall and weighed 60 kg before pregnancy. Her BMI is 60 ÷ 1.65² = 22.0, which is in the normal weight row. For one baby the CDC range is 25 to 35 pounds (11.3 to 15.9 kg). For twins the range is 37 to 54 pounds (16.8 to 24.5 kg). If she now weighs 65 kg, the readout shows +5.0 kg (11.0 lb) since before pregnancy. It is not a verdict on whether she is on track.
The kilogram figures are converted from the same pound endpoints that the CDC publishes, using 1 pound = 0.45359237 kg, so the two units always describe the same range. Underweight: 28 to 40 lb (12.7 to 18.1 kg) for one baby; Normal weight: 25 to 35 lb (11.3 to 15.9 kg) for one baby; Overweight: 15 to 25 lb (6.8 to 11.3 kg) for one baby; Obesity: 11 to 20 lb (5.0 to 9.1 kg) for one baby.
What this page does not do
This first version gives total ranges only. It does not draw a week-by-week trajectory, because the CDC table gives ranges for the whole pregnancy and a straight line between zero and the total would suggest a precision that the source does not claim. It also does not cover triplets or more, calorie targets or diet advice. The CDC publishes printable pregnancy weight gain trackers for one baby and for twins, by weight category, if you want a sheet to keep your own record; they are linked from the CDC page named below.
To work out your due date and how many weeks pregnant you are, use the pregnancy due date calculator. The Fitness & Health calculators page lists the other health tools on this site.
Limits you should know about
- These are population ranges. Individual care can differ because of age, health conditions, how the pregnancy is going and what your clinician advises. Follow your own clinician's guidance.
- BMI is a screening number. It does not describe your body composition or your health.
- Adults only. The calculator is built for adult inputs. Pregnant teenagers should use guidance from their own clinician.
- No promises. The page does not predict birth weight, outcomes or the right amount of weight gain for you.
Frequently asked questions
How much weight should I gain during pregnancy?
The CDC lists a total range for each prepregnancy BMI category and for one baby or twins. Your own clinician may recommend something different for you, and that advice is the one to follow.
Which weight do I enter first?
Your weight before you were pregnant. The ranges are defined by prepregnancy BMI, not by your current BMI.
Why is there no numeric range for my BMI?
The CDC table used here covers a prepregnancy BMI up to 39.9 and covers one baby or twins only. For a BMI of 40 or more, or for triplets or more, talk to your healthcare provider.
Does the current weight box tell me if I am gaining too much or too little?
No. It only shows the change since before pregnancy. The ranges describe the whole pregnancy, so a number from partway through cannot be judged against them.
What if I lost weight in early pregnancy?
The change is shown as a negative number without comment. Mention it to your clinician, who can tell you what it means in your case.
Sources and limits of this page
Ranges and category definitions follow the CDC page Weight Gain During Pregnancy (checked 10 November 2026), which draws on the Institute of Medicine's 2009 recommendations and, for underweight women with twins, Luke B et al., Journal of Reproductive Medicine, 2003. This page is educational information, not medical advice, and it has not been reviewed by a clinician.