Diaper Calculator
Estimate how many diapers you'll go through in year one — by size, with a size-by-weight chart and a total cost.
2,949
diapers · year one
≈ $590 total
How many of each size you'll need
Newborn · under 10 lb
Newborn (0–1 mo) · ~11/day
334
Size 1 · 8–14 lb
1–4 months · ~9/day
821
Size 2 · 12–18 lb
4–7 months · ~8/day
730
Size 3 · 16–28 lb
7–12 months · ~7/day
1,064
Diaper size by weight chart
| Size | Baby's weight | Typical age |
|---|---|---|
| Preemie | under 6 lb | Premature |
| Newborn | under 10 lb | 0–1 month |
| Size 1 | 8–14 lb | 1–4 months |
| Size 2 | 12–18 lb | 4–7 months |
| Size 3 | 16–28 lb | 7–18 months |
| Size 4 | 22–37 lb | 18–36 months |
| Size 5 | 27 lb + | 3 years + |
| Size 6 | 35 lb + | 4 years + |
Weights are brand-averaged guides — go up a size when diapers leave red marks or leak, not strictly by age.
Frequently asked
How many diapers does a baby use in the first year?
Most babies use roughly 2,500–3,000 diapers in their first year — about 10–12 a day as a newborn, dropping to 6–8 a day by their first birthday.
What size diaper for my baby's weight?
Newborn fits under 10 lb, Size 1 is 8–14 lb, Size 2 is 12–18 lb, Size 3 is 16–28 lb, Size 4 is 22–37 lb. Move up a size when you see red marks or leaks rather than by age alone.
How many newborn diapers should I buy before birth?
Buy only one small pack of Newborn size — many babies move into Size 1 within a few weeks (or are born already needing it). Stock more Size 1 instead.