Enter your baby's age and current weight to find the right diaper size and how many diapers you'll need per day, per week, and per month. The Diaper Calculator also estimates your monthly cost so you can plan and stock up with confidence.
Recommended Diaper Size
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Diapers Per Day
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Diapers Per Month
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Estimated Monthly Cost
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Newborns (0–3 months) typically need about 8–10 diapers per day. Their digestive systems are very active in the early weeks, meaning frequent changes are completely normal. As your baby grows, the number gradually decreases.
Diaper sizes are based on your baby's weight, not age. Size Newborn fits up to 10 lbs, Size 1 fits 8–14 lbs, Size 2 fits 12–18 lbs, Size 3 fits 16–28 lbs, Size 4 fits 22–37 lbs, Size 5 fits over 27 lbs, and Size 6 fits over 35 lbs. When in doubt between two sizes, try the larger one.
Signs your baby needs a bigger size include: frequent leaks or blowouts, red marks on the thighs or waist from the elastic, difficulty fastening the tabs comfortably, or if the diaper looks too snug. It's always better to size up a little early than to wait.
A well-fitting diaper should lie flat against your baby's tummy without gaps, the leg cuffs should be tucked out (not folded in), and you should be able to fit two fingers under the waistband. There should be no red marks from the tabs or leg elastics.
For a wet-only diaper, you have a short window — but you should still change it promptly, especially for newborns. Prolonged exposure to moisture can irritate sensitive skin and cause diaper rash. Soiled diapers should always be changed immediately.
For the first month, budget roughly 240–300 diapers (Newborn or Size 1). Avoid buying too many Newborn-size packs before birth since babies can outgrow them within weeks. Stock up on Size 1 and Size 2 instead, as those tend to last longer.
Divide your monthly diaper count by the number of diapers per box. For example, if your baby needs 200 diapers per month and each box contains 100 diapers, you need 2 boxes per month. Our calculator estimates your total monthly count based on your baby's age and weight.
Yes — newborns should be changed during nighttime feedings because they soil diapers frequently and their skin is very sensitive. As your baby gets older and starts sleeping longer stretches, you may be able to use overnight diapers and reduce nighttime changes.