Diaper Size Calculator
Find the right diaper size for your baby based on weight. Includes signs it is time to size up.
Results
Visualization
How It Works
Diaper sizes are based on weight, not age. Most brands follow similar sizing: N (up to 10 lbs), Size 1 (8-14 lbs), Size 2 (12-18 lbs), Size 3 (16-28 lbs), Size 4 (22-37 lbs), Size 5 (27+ lbs), Size 6 (35+ lbs). When in doubt, size up. Not medical advice.
The Formula
Size by weight (pounds):
N: up to 10 | Size 1: 8-14 | Size 2: 12-18
Size 3: 16-28 | Size 4: 22-37 | Size 5: 27+ | Size 6: 35+
N: up to 10 | Size 1: 8-14 | Size 2: 12-18
Size 3: 16-28 | Size 4: 22-37 | Size 5: 27+ | Size 6: 35+
Variables
- Size overlap — Sizes overlap because fit varies by baby body type
- Diapers/day — 8-12 for newborns, decreasing to 6-8 by 12 months
Example
14 lb baby: Size 2 diapers (12-18 lb range), approximately 10 diapers per day.
Tips
- Signs to size up: red marks on legs/waist, frequent blowouts, diaper hard to fasten
- For overnight, go one size up for extra absorbency
- Overlap zones (e.g., 14 lbs is both Size 1 and Size 2) -- go with what fits better
- Stock up on Size 3 and 4 -- babies spend the most time in these sizes