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Diaper size chart

Diaper sizes go by weight, not age: Newborn fits up to 10 lb, then Size 1 (8–14 lb) through Size 6 (35 lb+). The ranges overlap, so go by fit — snug legs, no leaks, no red marks — and size up the moment the current one leaves marks. Below is the full chart, plus the cheapest real cost per diaper we track at each size.

SizeWeightApprox. ageDiapers/dayCheapest we track
Newborn (N)Up to 10 lb0–6 weeks8–12$0.56/diaper →
Size 18–14 lb2–4 months8–10—
Size 212–18 lb4–7 months8–9$0.12/diaper →
Size 316–28 lb7–20 months6–7$0.52/diaper →
Size 422–37 lb18–36 months6$0.21/diaper →
Size 527+ lb3 years+5–6$0.25/diaper →
Size 635+ lb4 years+5$0.12/diaper →

Weight ranges are the common values across Pampers, Huggies, Luvs and store brands (they vary by a pound or two). Prices are the cheapest real cost per diaper we track at each size, live from Amazon US, re-checked on a rolling cycle; a dash means we don’t track enough of that size yet.

Cheapest diapers right now

Live from the catalog, ranked by real cost per diaper — cheapest first.

Go by fit, not the number

The single most useful thing to know about diaper sizing: the weight range is a guide, and the overlap is deliberate. A diaper that fits is one with snug (not tight) leg cuffs, tabs that reach the middle of the front, and no red marks when you take it off. If it leaks or marks the skin, size up — even if the baby is under the weight limit. Most overnight leaks are a fit problem, and sizing up fixes them.

Don’t stockpile a size — especially Newborn, which many babies wear for only 2–4 weeks. Buy one box, keep the receipt, and scale up once you know how your baby grows.

Keep going

Cheapest diapers by cost per diaperEvery size, ranked by real unit price.Open How much a newborn costs per monthDiapers, formula and wipes, from live prices.Read

Frequently asked

What weight is each diaper size?▾

Newborn fits up to 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, Size 5 is 27 lb and up, and Size 6 is 35 lb and up. The ranges overlap on purpose — go by the fit (snug legs, no red marks, no leaks) more than the number, and size up when the current one leaves marks or leaks.

How do I know when to move up a diaper size?▾

Move up when you see red marks on the legs or waist, gaps or leaks, or the tabs no longer reach the middle of the front. Babies are usually ready before they hit the top of the weight range. Sizing up often fixes overnight leaks even before the weight suggests it.

Does cost per diaper change by size?▾

Yes — larger sizes hold more diapers-per-dollar variation, and the count per box drops as the size goes up, so cost per diaper generally rises with size. That is exactly why the price to compare is cost per diaper, not the box price: a "mega" box of a big size can cost more per change than a smaller box.