Pregnancy weight gain calculator
Your healthy range, week by week.
Enter your height and weight before pregnancy. See the Institute of Medicine range for every week.
Recommended total gain by week 40
25–35lb
Your pre-pregnancy BMI is 23.3 (healthy weight range, 18.5 to 24.9). In the 2nd and 3rd trimesters, the guideline pace is about 0.8 to 1.0 lb a week.
Under 20 or shorter than 4 ft 10 in? The ranges have no separate guidance for you. Ask your care team.
The guideline
Total gain by pre-pregnancy BMI
From the Institute of Medicine’s 2009 report, which ACOG uses. Need your BMI? Work it out here.
| BMI before pregnancy | One baby | Weekly, 2nd and 3rd trimester | Twins |
|---|---|---|---|
| Underweight Below 18.5 | 28–40 lb 12.5–18 kg | 1–1.3 lb 0.44–0.58 kg | No guideline |
| Healthy weight 18.5 to 24.9 | 25–35 lb 11.5–16 kg | 0.8–1 lb 0.35–0.5 kg | 37–54 lb 17–25 kg |
| Overweight 25.0 to 29.9 | 15–25 lb 7–11.5 kg | 0.5–0.7 lb 0.23–0.33 kg | 31–50 lb 14–23 kg |
| Obese 30.0 or more | 11–20 lb 5–9 kg | 0.4–0.6 lb 0.17–0.27 kg | 25–42 lb 11–19 kg |
In the Alma app
Pregnancy nutrition, set up for you.
- Choose Pregnancy nutrition as your goal.
- Alma turns calorie counting off by default and applies pregnancy nutrient targets.
- Caffeine starts at a 200 mg daily default.
- Alma’s coach never suggests fasting or a calorie deficit.
Questions
What people ask
How much weight should I gain during pregnancy?
It depends on your BMI before pregnancy. For one baby, the Institute of Medicine recommends 28 to 40 lb for an underweight BMI, 25 to 35 lb for a healthy BMI, 15 to 25 lb for an overweight BMI, and 11 to 20 lb for an obese BMI. ACOG endorses these ranges.
Why does the calculator use my weight before pregnancy?
The ranges are set by pre-pregnancy BMI. Your weight today includes the baby, placenta, fluid and blood volume, so it can’t place you in a category.
How much should I gain in the first trimester?
The guidelines assume a total of about 1.1 to 4.4 lb (0.5 to 2 kg) across the first trimester. Most gain comes in the 2nd and 3rd trimesters.
How much weight should I gain with twins?
The Institute of Medicine’s provisional twin ranges are 37 to 54 lb for a healthy BMI, 31 to 50 lb for an overweight BMI, and 25 to 42 lb for an obese BMI. It set no range for an underweight BMI.
How is the weekly range drawn?
The chart rises from zero to the first-trimester amount at week 13. It then rises in a straight line to your total at week 40. The guidelines assume steady gain after the first trimester, but real weeks vary.
What if I’m outside the range?
Gain comes unevenly, and one reading says little on its own. Share your numbers with your care team. They know your pregnancy and can tell you what your trend means.
Sources
Written by Alma from the primary sources below and reviewed November 13, 2026. The weekly band is Alma’s estimate between the guideline’s first-trimester and term amounts. This is general information, not medical advice. Your care team knows your pregnancy, so check questions with them. Editorial standards
Eat well for two, without the guesswork.
Choose Pregnancy nutrition as your goal, and Alma applies pregnancy nutrient targets to every meal you log.