The short answer
Newborns go through a lot of diapers: the AAP says parents change as many as 8 to 12 a day, and nearly 3,000 in the first year. How many are newborn size depends mostly on how big your baby is at birth and how fast they grow, because sizes go by weight, not age.
For a baby born at the average weight (7 lb 4 oz), our calculator puts newborn size at about 3 weeks and 240 diapers. A baby born at 9 lb or more may skip newborn size entirely. A smaller baby can stay in it for 5 weeks or more.
How many to buy before your baby arrives
Buy about half of your newborn estimate before the birth, in one brand. Then wait. Once your baby is home you will know whether that brand fits without leaks and how fast they are growing, and you can buy the rest in the right size. Hold off on stocking up on Size 1 and above until you are close to needing it.
Newborn-size boxes come in different counts, so compare the number of diapers, not the number of boxes.
When to move up a size
Weight is only a guide. Pampers lists these signs that a diaper is too small:
- Red marks on the thighs or waist
- Leaks or blowouts, even when it is fastened properly
- Tabs that no longer reach the middle of the waistband
- The diaper no longer covers your baby's bottom
When your baby is in the overlap between two sizes, Pampers suggests trying both and keeping the one that fits. That's why our calculator moves up halfway through each overlap. Source: Pampers on when to size up.
Diaper sizes by weight
| Size | Pampers | Huggies |
|---|---|---|
| Newborn | Up to 10 lb | Up to 10 lb |
| Size 1 | 8–14 lb | 8–14 lb |
| Size 2 | 10–22 lb | 12–18 lb |
| Size 3 | 13–26 lb | 16–28 lb |
| Size 4 | 15–34 lb | 22–37 lb |
From each brand's US size chart, checked October 12, 2026: Pampers, Huggies. Both also make a preemie size, for babies up to 6 lb. Always follow the weight range printed on the package.
How many wipes
We assume 3 wipes per change, which comes to about 8,400 wipes in the first year. Messy changes take more, wet ones fewer. Change the number in "Change our assumptions" above if your habit is different. Wipes don't come in sizes, so they are safe to buy in bulk once you know your baby's skin is happy with them.
How we calculate
- Growth. We use the WHO Child Growth Standards for weight-for-age, which the CDC recommends for babies under 2, from the CDC's data files. Your baby's birth weight sets their starting percentile, and we assume they stay on it. Real babies wander between percentiles, so treat the dates as a rough guide.
- Sizes. Each brand's published weight ranges. Where two sizes overlap, we move up halfway through the overlap.
- Diapers a day. Our planning assumption: 10 a day in the first month (the AAP gives 8 to 12), 8 a day to 6 months, and 7 a day to 12 months. That adds up to about 2,800 in the first year, in line with the AAP's "nearly 3,000". You can change all three.
- Rounding. Results are rounded to the nearest 10, or 100 above 1,000.
A note on health. In the first days, your pediatrician may ask how many wet and dirty diapers your baby has, as a sign that feeding is going well. This calculator is for shopping, not for that. If you are worried about your baby's diapers, feeding or weight, call your pediatrician.
Next on your list
See when newborn diapers, Size 1 and everything else fit into your weeks in the Due-Date Plan.