Pregnancy weight gain calculator
Enter your height and pre-pregnancy weight to see the recommended total gain for your BMI, and check where you are this week.
- Suggested gain by week 20
- 7 lb – 12 lb
IOM 2009 weight gain guidelines
| Pre-pregnancy BMI | Total gain (single) | Per week, 2nd–3rd trimester | Total gain (twins) |
|---|---|---|---|
| Under 18.5 | 28–40 lb (12.5–18 kg) | 1–1.3 lb | no guideline |
| 18.5–24.9 | 25–35 lb (11.5–16 kg) | 0.8–1 lb | 37–54 lb |
| 25–29.9 | 15–25 lb (7–11.5 kg) | 0.5–0.7 lb | 31–50 lb |
| 30 and above | 11–20 lb (5–9 kg) | 0.4–0.6 lb | 25–42 lb |
Source: Institute of Medicine (now National Academy of Medicine), "Weight Gain During Pregnancy: Reexamining the Guidelines", 2009; endorsed by ACOG Committee Opinion 548.
Frequently asked questions
How much weight should I gain during pregnancy?
It depends on your pre-pregnancy BMI. The US Institute of Medicine (2009) recommends 28–40 lb for underweight (BMI under 18.5), 25–35 lb for a healthy weight (18.5–24.9), 15–25 lb for overweight (25–29.9) and 11–20 lb for obesity (30 or more), for a single baby.
How much weight do you gain in the first trimester?
Only about 1–4.5 lb (0.5–2 kg) in total, and some people lose weight because of nausea. Most gain happens in the second and third trimesters, at roughly 0.5–1 lb a week depending on BMI.
Where does pregnancy weight go?
At term, a typical gain is roughly: baby 7–8 lb, placenta 1–2 lb, amniotic fluid 2 lb, larger uterus 2 lb, breast tissue 1–3 lb, extra blood 3–4 lb, other fluid 2–3 lb and fat stores 6–8 lb.
What about twins?
The IOM's provisional guidelines for twins are 37–54 lb for a healthy BMI, 31–50 lb for overweight and 25–42 lb for obesity. There isn't enough evidence for an underweight twin recommendation, so ask your provider.