Pregnancy Weight Gain Calculator
How much gain is typical for your starting point? IOM ranges by pre-pregnancy BMI, with a gentle pace-check at your current week.
These are population-level ranges from the Institute of Medicine, not personal targets. Gain outside them is common and usually fine — your provider tracks your trend, your baby's growth and your health together.
Where the numbers come from
The IOM (now National Academy of Medicine) ranges, used across US prenatal care:
| Pre-pregnancy BMI | Category | Total gain (single baby) |
|---|---|---|
| Below 18.5 | Underweight | 28-40 lb |
| 18.5-24.9 | Normal | 25-35 lb |
| 25.0-29.9 | Overweight | 15-25 lb |
| 30 and above | Obese | 11-20 lb |
Pace matters as much as the total: little gain in the first trimester, then roughly a pound a week (half a pound if overweight or obese) through the second and third.
Questions people ask
I'm gaining faster than the range — should I diet?
No. Pregnancy is not the time for caloric restriction. Mention the trend at your next visit; providers adjust guidance individually, and many factors — swelling, twins, fluid — move the number.
Does this work for twins?
Yes — switch Pregnancy type to Twins. IOM twin ranges are higher: 50-62 lb if underweight, 37-54 lb at normal weight, 31-50 lb if overweight, and 25-42 lb with obesity. Twins gain on a different weekly schedule, so we show the total target and leave the pacing to your provider.
What if I've lost weight from morning sickness?
Losing a few pounds in the first trimester is common with severe nausea and usually harmless — the baby takes what it needs. Tell your provider if you cannot keep fluids down.