🤰 Pregnancy Weight Gain Calculator
How much weight should you gain during pregnancy? It depends on your BMI before pregnancy. This calculator follows the 2009 Institute of Medicine (IOM) guidelines for a single baby.
How the Pregnancy Weight Gain Calculator works
Your pre-pregnancy BMI sets the total range. A gain of about 1.1–4.4 lb (0.5–2 kg) is expected in the first trimester, then a weekly rate for your BMI group from week 14 onward.
Step-by-step calculation
- 1Enter pre-pregnancy weight and height.
- 2Calculate BMI.
- 3Match to IOM total gain range.
- 4Estimate a typical range for your week.
Worked example
A 140 lb, 5 ft 5 in woman has a pre-pregnancy BMI of 23.3 (normal), so the total goal is 25–35 lb, and at week 20 a typical gain is about 6.7–11.4 lb.
Pregnancy Weight Gain Calculator examples
| Weight before pregnancy | Recommended total gain |
|---|---|
| 70 | 28–40 lb total |
| 105 | 28–40 lb total |
| 140 | 25–35 lb total |
| 175 | 15–25 lb total |
| 210 | 11–20 lb total |
Other inputs kept at the calculator's default values. Results calculated by this calculator.
Why use a Pregnancy Weight Gain Calculator?
See a healthy weight gain range for your pregnancy.
Important factors that can affect your results
- Twins have different ranges.
- Nausea in the first trimester.
- Your care provider's guidance.
Frequently asked questions
What about twins?
Guidelines are different for twins. Ask your doctor or midwife.
I am outside the range. Should I worry?
Not necessarily. Every pregnancy is different — talk to your care provider before changing what you eat.
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Last reviewed November 2026 · How we build and check our tools · Report a problem