Diaper Size Calculator
Sizes differ by brand, and they overlap. Enter a weight to see which ones fit and which to buy first.
How many diapers in the first year?
Using Huggies’ own published diapers-per-day and months-in-size figures. Every baby differs, so treat the totals as a stocking-up guide, not a shopping list.
1,950 diapers in the first year, give or take a few boxes
Buy Newborn and Size 1 in small packs only: many babies are out of them within weeks. For what this costs month by month, use the Baby Budget Calculator.
How diaper sizes work
Every disposable diaper is sized by weight. The box prints a range, the ranges of neighboring sizes overlap on purpose, and no brand publishes a height or age chart. Two babies born the same week can wear different sizes, and the same baby can land on different sizes at Huggies and Pampers, because since 2026 the two brands no longer print the same ranges.
Huggies diaper size chart by weight
Huggies prints the classic ranges most store and value brands also use. Per-day and time-in-size figures are Huggies’ own published averages. Huggies also sells a Size 8 from 46 lb.
Pampers diaper size chart by weight (2026 ranges)
Pampers widened every range from Size 2 upward in 2026 and added a Size 8. Size 3 now starts at 13 lb instead of 16, Size 4 at 15 lb instead of 22, and Size 5 at 20 lb instead of 27. Per-day figures are printed as “up to”; time in size is Pampers’ own average. The same chart appears on the Swaddlers and Baby Dry product pages.
The practical effect: a 24 lb baby sits in Size 3 or 4 on the Huggies chart and in Sizes 3 through 6 on the Pampers chart. The calculator picks a starting size, but with Pampers the fit check below matters more than the number.
Brands that do not use the classic ranges
Most store and value brands print the classic ranges, and so does The Honest Company. Two of the newer premium brands do not, which is why the calculator carries their own charts rather than a single universal one.
Coterie
Narrower through Size 4. Size 1 is 8 to 12 lb, Size 2 is 10 to 16 lb, Size 3 is 14 to 24 lb and Size 4 is 20 to 32 lb. A 15 lb baby is in Size 2 at Huggies, while here it is covered by both Size 2 and Size 3.
Millie Moon
Every boundary differs. Newborn stops under 9 lb, Size 1 starts at 6 lb, and the sizes stay closed-ended to Size 6. Millie Moon also gives the opposite overlap advice to everyone else: when two of its sizes match, take the smaller one, because their diapers run slightly large. The calculator follows that advice for this brand.
Two sizes fit. Which one?
Both manufacturers give the same answer. Pampers: “If your baby is between sizes, check the diaper fit to decide.” Huggies: “Some sizes overlap. Check fit to know when to move up a size.” In practice:
- While the weight is in the lower part of the smaller size’s range, start there. It is cheaper per diaper and usually seals better on a smaller frame.
- Once the weight is well up the range (the calculator uses about two thirds), start with the larger size. You will be there for months anyway.
- If your baby already wears the larger size without gaps at the legs or leaks, stay there. Going back down because a chart says so only buys red marks.
- Whatever the chart says, red marks, leaks, or tabs that barely reach mean move up now.
Worked example
Your baby weighs 24 lb (10.9 kg) and wears Huggies Size 4:
- On the Huggies chart, 24 lb is covered by Size 3 (16 to 28 lb) and Size 4 (22 to 37 lb).
- 24 lb is two thirds of the way up Size 3, so Size 4 is the better place to be. It has about 13 lb of room.
- Since Size 4 is already on, the answer is simply: stay. Size 3 fits on paper, but there is no reason to size down.
- On the Pampers chart the same weight falls inside Sizes 3, 4, 5 and 6; the calculator starts at Size 4 and lets the fit decide.
Why height is not an input
Parents ask, reasonably, why a tall baby and a short baby of the same weight get the same answer. Because that is how the products are sized: weight is the only number the manufacturers test against, and none of them publishes a height range. Body shape does change the fit, and Huggies says so directly: a long, lean baby may need a smaller size, while an active, heavier baby may size up faster. The calculator’s job is to show the sizes the weight allows; the fit check picks between them.
How to weigh a baby at home
Step on a bathroom scale alone, then again holding your baby, and subtract. It is accurate to about half a pound, which is plenty for diaper sizing. Clinic weights from the last check-up work too, as long as they are recent: babies in Size 1 and 2 can gain a pound every two weeks.
Frequently asked questions
What size diaper does my baby need?
Diapers are sized by weight, not age. On the Huggies chart: Newborn up to 10 lb, Size 1 is 8 to 14 lb, Size 2 is 12 to 18 lb, Size 3 is 16 to 28 lb, Size 4 is 22 to 37 lb, Size 5 is 27 lb and up, Size 6 is 35 lb and up, Size 7 is 41 lb and up, Size 8 is 46 lb and up. Pampers prints wider ranges since 2026, so check the brand on the box. Enter the weight above to see every size that fits.
My baby’s weight is in two sizes. Which one do I buy?
Both brands say the same thing: the overlap is on purpose, so check the fit. Start with the smaller size while the weight is in the lower part of its range, and move up at the first red marks, leaks or tabs that barely reach. If the weight is already well up the smaller size’s range, start with the larger one. If your baby already wears the larger size comfortably, stay there; there is no reason to size down.
Are Huggies and Pampers sizes the same?
Not any more. Huggies still prints the classic ranges (Size 3 is 16 to 28 lb, Size 4 is 22 to 37 lb). Pampers widened its ranges in 2026: Size 3 is 13 to 26 lb, Size 4 is 15 to 34 lb, Size 5 is 20 to 37 lb, Size 6 is 23 to 44 lb, Size 7 is 26 to 50 lb, and there is a Size 8 from 30 lb. The same 24 lb baby is covered by Sizes 3 and 4 at Huggies, and by Sizes 3, 4, 5 and 6 at Pampers.
Does height or body shape change the diaper size?
No brand publishes a height chart; weight is the only number on the box. Shape still matters. Huggies notes that a long, lean baby may need a smaller size and an active, heavier baby may size up faster. If a size that matches the weight leaks or leaves marks, change the size or try another brand’s cut rather than second-guessing the scale.
Do all brands use the same weight ranges?
No. Huggies, The Honest Company and most store and value brands print the classic ranges. Pampers widened its ranges in 2026. Coterie runs narrower through Size 4 (Size 3 is 14 to 24 lb), and Millie Moon sets every boundary differently, with Newborn stopping under 9 lb. Pick the brand on the box before you read a size off any chart.
When should I size up diapers?
Move up when you see red marks on the waist or thighs, leaks or blowouts (especially overnight), tabs that fasten right at the edge, a diaper that no longer covers the whole bottom, or a weight at the top of the current range. Many parents buy the next size a few pounds early so the last box of the old size does not go to waste.
What diaper size is best for a newborn?
Most full-term babies start in Newborn, which both brands print as up to 10 lb. Babies born over about 9 lb often skip straight to Size 1 (8 to 14 lb). Babies under 6 lb usually need Preemie diapers; the hospital or your pediatric team will say which size to take home.
How many diapers does a baby use in the first year?
Using each brand’s own published figures, the first year comes to roughly 1,950 diapers on the Huggies chart. The Pampers chart gives about 2,900, but that is a ceiling: Pampers prints its daily count as “up to”, while Huggies prints an average. Newborns use the most, 8 to 10 a day, falling to 4 or 5 a day by the first birthday. The plan on this page breaks the total down by size.
Can I work out the size from my baby’s age instead of weight?
Only as an estimate. The calculator can take an age in months and use the WHO median weight for that age, but the typical span at any age covers two or three diaper sizes, and the ruler shows that span. A recent weight from a check-up or a bathroom scale (weigh yourself, then yourself holding the baby) gives a real answer.
Related tools and reading
- Baby Budget Calculator turns the first-year diaper count into a monthly cost
- Growth Tracker and Baby BMI Calculator follow the weight that drives diaper sizing
- Formula Calculator for daily feeding amounts
- How to Plan for Financial Changes With a New Baby
- Baby Milestones in the First Year
Sources and method
Weight ranges, diapers-per-day and time-in-size figures were read from the manufacturers’ US pages in September 2026: Huggies diaper size chart by weight and Pampers diaper size and weight chart. The Honest Company, Coterie and Millie Moon charts come from honest.com, coterie.com and milliemoon.com. The “other brands” chart uses the classic ranges Huggies prints, which most store and value brands share; check your box, since a brand can change its chart at any time. Age estimates use the WHO Child Growth Standards weight-for-age medians (2006), the same tables as our growth tracker. The first-year plan multiplies each brand’s published per-day figure by its published months in size; it assumes nothing about your baby.
Note: this is a sizing guide, not medical advice. If a diaper leaves marks or leaks in every size, or your baby’s weight is far outside the typical span for their age, mention it at the next check-up.