Which diaper size actually fits?
Enter your baby’s weight and this diaper size calculator shows every size that covers it. Sizes go by weight, not age. They overlap, so two sizes often cover the same weight. From the Pampers United States chart, checked September 16, 2026.
Find the size
Where two fit, the bigger one holds more and the smaller one is less bulky. You’ll know which suits her after a night or two.
At 12 lb, it’s Size 1 or Size 2.
| Brand | Sizes that fit |
|---|---|
| Pampers | Size 1 8–14 lbSize 2 10–22 lb |
The full Pampers size chart
| Size | Weight | Metric |
|---|---|---|
| Preemie | under 6 lb | under 2.7 kg |
| Newborn | under 10 lb | under 4.5 kg |
| Size 1 | 8–14 lb | 3.6–6.4 kg |
| Size 2 | 10–22 lb | 4.5–10 kg |
| Size 3 | 13–26 lb | 5.9–11.8 kg |
| Size 4 | 15–34 lb | 6.8–15.4 kg |
| Size 5 | 20–37 lb | 9.1–16.8 kg |
| Size 6 | 23–44 lb | 10.4–20 kg |
| Size 7 | 26–50 lb | 11.8–22.7 kg |
| Size 8 | 30+ lb | 13.6+ kg |
From pampers.com, checked September 16, 2026. The pounds are theirs. We converted the kilograms.
Why do diaper sizes overlap?
Because each size is a range, and the ranges overlap. Pampers Size 1 covers 8–14 lb and Size 2 covers 10–22 lb, so a baby anywhere from 10 to 14 lb fits both.
Other brands and countries differ. The same size number can cover a different weight from one brand to the next, so if your pack doesn’t match the chart, go by the range printed on it.
Changed one at 4AM? Log it with one hand. Bundle of Joy keeps every diaper, pee, poop or both, and shows you and your partner how long it’s been since the last one, and how many today.
The other free tools
- WHO growth chart calculator. Plot a weight and get the percentile.
- Baby age calculator. Days, weeks, months and corrected age.
- Baby weight converter. Kilograms to pounds and ounces.
- Formula amount calculator. What the AAP and NHS guidelines say for a weight.
- Newborn diaper chart. Wet and dirty diapers by day, and poop colors, from the CDC, the AAP and the NHS.
The last diaper, at a glance.
Every change on both your phones, with how long it’s been.
