Pregnancy Weight Gain Calculator
Find out how much weight you should have gained by now and by full term, following Institute of Medicine (IOM) recommendations scaled to your pre-pregnancy BMI and week of pregnancy.
Pre-pregnancy BMI
22.8 (Normal weight)
Total recommended gain
11.5 - 16 kg
Recommended gain by week 20
3.4 - 4.7 kg
Based on Institute of Medicine (IOM) 2009 guidelines. Roughly 0.4-0.5 kg per week is typical in the second and third trimesters.
How to Use the Pregnancy Weight Gain Calculator
- Enter your height and weight just before pregnancy to get your pre-pregnancy BMI.
- Select single or twins and enter your current week of pregnancy.
- View the total target range and the week-by-week recommended gain so far.
Formulas Used
Underweight (BMI <18.5): gain 12.5-18 kg (28-40 lb)
Normal (BMI 18.5-24.9): gain 11.5-16 kg (25-35 lb)
Overweight (BMI 25-29.9): gain 7-11.5 kg (15-25 lb) | Obese (BMI ≥30): 5-9 kg (11-20 lb)
Twins: underweight 22.5-28 kg | normal 17-25 kg | overweight 14-23 kg | obese 11-19 kg
Frequently Asked Questions
Where do these pregnancy weight gain ranges come from?
From the 2009 Institute of Medicine / National Research Council guidelines, still the standard reference used by most obstetric providers in the United States.
Does the baby account for all the weight gained?
No. At term, roughly 3-4 kg is baby, plus placenta, amniotic fluid, expanded blood volume, uterus growth and stored fat for breastfeeding.
What if my gain is outside the range?
Week-to-week variation is normal. Consistently gaining much faster or slower than recommended is worth discussing with your provider, who can tailor advice to your situation.
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