How the calculator works
Diaper sizes are set by weight, and the ranges overlap on purpose because babies are built differently. The calculator checks your baby's weight against the Pampers and Huggies size charts and recommends the smallest size that fits by weight with room to grow. Brands advise against sizing up too early, so that's the usual starting point. Any other size that also fits by weight is flagged as an overlap zone, where fit decides.
The optional estimate converts your baby's weight to a z-score (a percentile) on the WHO weight-for-age standards, then finds the age at which a baby on that same percentile reaches the next size's weight. It works from birth to age 5, the range of the WHO standards. If your baby was born early, enter the due date instead of the birth date, since growth is judged by corrected age for the first 2 years. To see the percentile itself, use the baby weight percentile calculator. For typical weights and monthly gains, see average baby weight by month and baby weight gain per month.
Diaper size chart by weight: Pampers vs Huggies
Weight ranges for each brand's standard taped diapers, as printed on their size charts. Kilograms are converted from pounds.
| Size | Pampers | Huggies |
|---|---|---|
| Preemie | Under 6 lb (2.7 kg) | Under 6 lb (2.7 kg) |
| Newborn | Under 10 lb (4.5 kg) | Under 10 lb (4.5 kg) |
| Size 1 | 8–14 lb (3.6–6.4 kg) | 8–14 lb (3.6–6.4 kg) |
| Size 2 | 10–22 lb (4.5–10 kg) | 12–18 lb (5.4–8.2 kg) |
| Size 3 | 13–26 lb (5.9–11.8 kg) | 16–28 lb (7.3–12.7 kg) |
| Size 4 | 15–34 lb (6.8–15.4 kg) | 22–37 lb (10–16.8 kg) |
| Size 5 | 20–37 lb (9.1–16.8 kg) | 27+ lb (12.2+ kg) |
| Size 6 | 23–44 lb (10.4–20 kg) | 35+ lb (15.9+ kg) |
| Size 7 | 26–50 lb (11.8–22.7 kg) | 41+ lb (18.6+ kg) |
| Size 8 | 30+ lb (13.6+ kg) | 46+ lb (20.9+ kg) |
Sources: Pampers size chart (same ranges on Swaddlers and Baby-Dry); Huggies Snug & Dry and Little Snugglers size charts. Checked November 2026.
- Ranges vary by product line. Pampers' pull-on Cruisers 360 list Size 3 as 16–28 lb and Size 4 as 22–37 lb, and Huggies' Skin Essentials product page lists Newborn as 6–9 lb. The package is the final word.
- Preemies: Pampers says it makes four different preemie sizes for the tiniest babies.
- Not sure your baby is getting enough milk? Count wet diapers, not sizes: see wet and dirty diapers by age and signs your baby is getting enough breast milk.
Frequently Asked Questions
What size diaper does a newborn wear?▾
Newborn size is for babies under 10 lb at both Pampers and Huggies, and preemie size is for babies under 6 lb. Pampers notes that many babies outgrow newborn size within the first month and that you may switch to Size 1 (8–14 lb) at around 8 lb if your baby is growing quickly. Fit matters more than the date.
How do I know when to size up diapers?▾
Watch for frequent leaks or blowouts, red marks on the thighs or waist, tabs that barely reach the center of the waistband, a waistband you can't fit two fingers under, or a diaper that no longer covers your baby's bottom. Pampers suggests moving up when your baby is in the next size's weight range and the diaper fits tight, marks the skin or leaks.
Why don't Pampers and Huggies sizes match?▾
Each brand sets its own weight ranges. Pampers Size 2 is 10–22 lb, while Huggies Size 2 is 12–18 lb, and from Size 5 up Huggies lists open-ended ranges such as 27+ lb. Ranges can also differ between product lines from the same brand, such as Pampers' pull-on Cruisers 360, so always check the package.
Should I choose a diaper size by weight or by age?▾
By weight, then fit. Babies grow at different rates: Pampers points out that one 3-month-old may still be in newborn diapers while another is already in Size 2. Age-based charts are only a rough guide, and the weight ranges printed on the package are what the brands design each size for.
How does the next-size estimate work?▾
If you add your baby's sex and date of birth, the calculator finds your baby's percentile on the WHO weight-for-age standards and assumes they keep growing along it. It then finds the age at which that percentile reaches the next size's weight range. Many babies shift percentiles in the first 2 years, so treat the result as a rough guide.
Sources
- Pampers: Diaper Size and Weight Chart (updated June 18, 2026)
- Pampers: Cruisers 360 product page (pull-on size ranges)
- Huggies: Snug & Dry diapers, size chart (Sizes 1–8)
- Huggies: Little Snugglers diapers, size chart (Preemie–Size 6)
- Huggies: Skin Essentials diapers (product size list)
- WHO Child Growth Standards: weight-for-age
- AAFP: Short and Tall Stature, a New Paradigm (2008), percentile shifts in the first 2 years
- AAP (HealthyChildren.org): Corrected Age for Preemies