Calculator
Pregnancy Weight Gain Calculator
Calculate your recommended weight gain during pregnancy using IOM guidelines based on your pre-pregnancy BMI. Track progress week by week.
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Pregnancy Weight Gain Calculator
Based on IOM (Institute of Medicine) guidelines. Enter your pre-pregnancy stats to see your personalized weight gain recommendations and track your progress.
📋Your Details
Expecting twins (+10 lbs to range)
🎯Your BMI & Recommendations
Pre-Pregnancy BMI
23.3
Normal weight
Recommended Total Gain
25.0–35.0 lbs
(11.3–15.9 kg)
Status at Week 20
above
Gained: 13.0 lbs (5.9 kg)
Actual Gain So Far
13.0 lbs / 5.90 kg
Expected Gain by Week 20
7.8–10.9 lbs
(midpoint: 9.3 lbs / 4.2 kg)
📊Week-by-Week Expected Gain
Expected gain at milestone weeks (based on midpoint of your recommended range). 1st trimester: gradual; 2nd & 3rd: ~1 lb/week.
| Week | Trimester | Expected Gain (lbs) | Expected Gain (kg) |
|---|---|---|---|
| Week 4 | T1 | 0.6 lbs | 0.3 kg |
| Week 8 | T1 | 1.3 lbs | 0.6 kg |
| Week 12 | T1 | 1.9 lbs | 0.9 kg |
| Week 16 | T2 | 5.2 lbs | 2.3 kg |
| Week 20 | T2 | 9.3 lbs | 4.2 kg |
| Week 24 | T2 | 13.4 lbs | 6.1 kg |
| Week 28 | T3 | 17.6 lbs | 8.0 kg |
| Week 32 | T3 | 21.7 lbs | 9.9 kg |
| Week 36 | T3 | 25.9 lbs | 11.7 kg |
| Week 40 | T3 | 30.0 lbs | 13.6 kg |
📋IOM Guidelines by BMI Category
| BMI Category | BMI Range | Gain (lbs) | Gain (kg) |
|---|---|---|---|
| Underweight | < 18.5 | 28–40 | 12.5–18 |
| Normal weight | 18.5–24.9 | 25–35 | 11.5–16 |
| Overweight | 25–29.9 | 15–25 | 7–11.5 |
| Obese | ≥ 30 | 11–20 | 5–9 |
| Twins (add ~10 lbs) | Any | +10 | +4.5 |
Source: Institute of Medicine (IOM) / National Academies 2009 guidelines. Always consult your healthcare provider for personalized guidance during pregnancy.