Diaper Size & Quantity Calculator

Enter your baby’s weight to see a suggested diaper size, and add their age in months to estimate how many diapers you’ll use a day, week and month. Handy for stocking up — or for deciding how many of each size to put on a registry.

Baby’s weight (kg)Age (months)

Estimates for planning only. Diaper sizing and usage vary by brand and baby — always check the pack’s weight range.

How it works

Diapers are sized by weight, not age, and the ranges overlap between brands. We map your baby’s weight to the typical size band, so you can buy with confidence and avoid over-stocking a size your baby is about to outgrow.

How many you’ll need drops quickly over the first year — from ten or more a day as a newborn to just a handful by their first birthday. Enter an age and we’ll turn a realistic daily range into weekly and monthly totals to plan around.

Frequently asked questions

How do I know what diaper size to buy? +

Go by your baby’s weight, not their age, and check the range on the pack — brands differ. If diapers leave red marks or leak around the legs, it’s usually time to size up.

How many diapers will I use a day? +

Newborns often need 10–12 a day; this drops to around 8 by a few months, and 5–6 by the end of the first year. Every baby is different — treat these as planning estimates.

Should I stock up on newborn diapers? +

Buy only a small pack of newborn size — many babies move into size 1 within weeks, and some skip newborn entirely. Keep more of sizes 1 and 2 on hand.

When should I move up a size? +

Size up when the current size leaves marks, leaks frequently, or the tabs barely reach. A bigger size that fits well usually leaks less, even before the weight cut-off.