Pregnancy Weight Gain Calculator (IOM 2009 Ranges)

How to use

1. Pick US (lb, ft/in) or metric units and enter your pre-pregnancy weight and height.
2. Add today's weight and the current week of pregnancy.
3. Read your IOM total range, the twin row if relevant, and the estimated cumulative window for this week.
4. Check the on-track / below / above indicator against your own gain so far.

General information only — not medical, financial or legal advice. Figures cross-checked against public official sources (IRS / HMRC / NHS / WHO guidance); content last reviewed September 2026. For decisions that matter, confirm with a licensed professional in your country.

About this tool

Recommended pregnancy weight gain depends on where you started: the IOM 2009 guidelines define total gain ranges by pre-pregnancy BMI — 28–40 lb for underweight, 25–35 lb for normal weight, 15–25 lb for overweight, and 11–20 lb for obesity, with higher totals for twins. This tool computes your pre-pregnancy BMI from weight and height (US or metric units), shows your full range plus a twin row, and estimates a cumulative window for the current week using the standard first-trimester assumption and the IOM weekly rates for the second and third trimesters. Your current weight is compared against that window for an on-track, below, or above indicator. Nausea, appetite, and fluid shifts make week-to-week movement bumpy, and the OB plan always overrides this chart. It is an educational estimate — not medical advice.

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