Newborn vs Size 1 Diapers: Which to Buy Before Birth

AvatarBySaima Mostari

Sources checked 2026-08-24.

Buy one pack of newborn size and build the rest of your stash in size 1. Newborn covers up to 10 lb and size 1 covers 8 to 14 lb, so they share only the band between 8 and 10 lb, and Pampers puts a typical stay in newborn size at two to four weeks. The part that decides it is not the two pounds, though. It is the umbilical cord notch cut into newborn diapers, and a rise short enough to stay below the cord stump. That is a feature with a deadline measured in days, not a size you grow into.

Newborn vs Size 1 Diapers, Which to Buy Before Birth

“Before birth, I suggest keeping one smaller pack of newborn diapers and putting most of the stash into size 1. Newborn diapers can be useful for the shorter rise and umbilical cord area during those first weeks, while size 1 usually becomes useful for much longer. I would rather keep that newborn pack sealed until I know the actual fit than overstock a size my baby may leave quickly.”

Newborn vs size 1: the two ranges, and the two pounds they share

Pampers publishes these ranges on its own newborn diapering guidance, and they matched the pack ranges we checked at Walmart, Kroger and Fred Meyer on 2026-08-23.

Size Weight range The feature that defines it
Newborn (N) Up to 10 lb Umbilical cord notch on the front waistband, shortest rise
Size 1 8 to 14 lb No notch on most lines, longer rise, more capacity

The overlap is 8 to 10 lb, which is two pounds wide. That is the narrowest overlap in the whole size range, and it is the reason this question feels decidable in a way that later size questions do not. Two pounds is a week or two of a newborn’s life, not a plateau.

The average baby starts below the size 1 floor

Here is the number that reframes the whole decision, and almost no buying guide states it.

Size 1 does not begin until 8 lb. The American Academy of Pediatrics, on HealthyChildren.org, writes that “the average full-term baby weighs about 7 pounds (3.17 kg) at birth”. An average birth weight therefore sits below the bottom of the size 1 range, not inside it.

So the real question is not “will my baby be big enough to skip newborn size”. It is “will my baby be born at 8 lb or more”, and against that average, buying only size 1 is a bet that your baby arrives on the heavier side. Plenty do. You will not know which until the day.

The umbilical cord notch is the actual difference

Weight is what the box argues about. The notch is what the diaper is for.

Pampers describes the feature plainly, saying certain newborn diapers include “an Umbilical Cord Notch to help protect your baby’s healing belly area”. It exists because of what the AAP asks parents to do in those first weeks. HealthyChildren.org tells parents to “keep the diaper folded below the cord to keep urine from soaking it”, and says there is no need to use alcohol on the stump, “just keep it clean”.

A diaper with a longer rise resists being folded down and creeps back up over the stump between changes. The notch removes that fight. That is a real, short-lived job, and it ends when the stump does. The AAP asks parents to seek medical advice if the stump has not fallen off by three weeks of age, and to call the pediatrician for foul-smelling discharge, redness around the base, or crying when the area is touched. Cord care is a conversation with your pediatrician, not a diaper purchase.

How long newborn size lasts

Pampers’ own answer is that “most babies wear size N for 2 to 4 weeks before moving to size 1”. Treat that as a manufacturer’s typical case rather than a schedule, because it depends entirely on birth weight and growth rate, and neither is known in advance.

What you can plan around is the shape of the risk. Buying too much newborn size wastes the packs you do not open. Buying none at all leaves you sending someone to a store during the first week home, which is the worst week to need an errand. The asymmetry favors having one pack you might not finish.

How many to buy before the birth

Newborns go through a lot of diapers, and the AAP gives a usable range on HealthyChildren.org, describing “as many as 8 to 12 a day once you get into the swing of things”, with the average settling at about six changes a day later on.

Do the arithmetic yourself rather than trusting a registry number. At the upper end of that range, a week is meaningful volume, and a newborn’s stay in that size may be two weeks or six. Three rules keep you out of trouble.

Keep the packs sealed until you need them, because an unopened pack is returnable and an opened one is not. Buy the smallest pack size for newborn and save the warehouse box for size 1, where your baby will spend far longer. And ask your birth hospital what they supply and what size, because the answer changes what you need in the house on day one.

When it makes sense to skip newborn size

Two situations point that way, and one of them is not really yours to judge.

If your care team has told you to expect a large baby, that changes the odds. A prenatal weight estimate is an estimate, though, and what it means for your plans is a question for your OB or midwife rather than for a size chart.

The other case is simpler. If your baby is already past the cord stump stage, which happens with a longer hospital stay, the notch has no job left to do, and the decision goes back to fit. That is where our diaper fit and leak troubleshooting guide picks up, because it routes each symptom to the thing that usually causes it.

What to do if you guessed wrong

Neither mistake is expensive if you catch it early, and both look like a leak before they look like a size.

If the size 1 you bought goes on your newborn but gaps at the legs and rides above the belly button, that is the signature of a diaper that is too big, and the full list is in our guide to the signs a diaper is too big. If the newborn pack starts leaving pressure lines and the tabs need a stretch to meet, your baby is done with it, and the checks are in how to tell if a diaper is too small. Neither is a reason to buy in a hurry: run the fit checks for a day first, because a diaper put on slightly wrong produces the same symptoms as a diaper in the wrong size.

FAQ

Can I skip newborn diapers entirely?
You can, and some parents do, but it is a bet on birth weight. Size 1 starts at 8 lb, and the AAP puts the average full-term birth weight at about 7 lb. Skipping newborn size also means giving up the umbilical cord notch during the weeks the AAP asks you to keep the diaper folded below the cord.

My baby is 9 lb. Which size, newborn or size 1?
Both ranges include 9 lb, so the chart cannot answer it. Decide on the cord and the fit. If the stump is still attached, the notch is worth having. If it has fallen off, check whether the tabs meet near the middle without a stretch and whether the leg cuffs sit on the thigh without a visible gap. Our page on the weight overlap between sizes works through the same tie-breakers in more detail.

How many newborn diapers should I have at home?
There is no single right number, and any guide that gives you one is guessing at your baby’s birth weight. Work from the AAP’s “as many as 8 to 12 a day” and your own tolerance for an errand in week one. One pack, unopened, with size 1 ready behind it, is the low-regret version.

Do all newborn diapers have the cord notch?
No. Pampers describes it as a feature of certain newborn diapers rather than of the size itself, so check the pack. Some newborn lines use a notch, some use a lower front waistband, and some have neither, which puts the folding job back on you.

Sources

  • Pampers, “How Many Newborn Diapers Do You Need?”, read 2026-08-24, for the newborn and size 1 weight ranges, the 2 to 4 week typical stay in newborn size, and the umbilical cord notch description.
  • HealthyChildren.org (American Academy of Pediatrics), “Caring for a Premature Baby” for average full-term birth weight, “Umbilical Cord Care in Newborns” for cord care and when to call, and “Changing Diapers” for daily change counts.
  • Pack weight ranges cross-checked against current US retailer listings at Walmart, Kroger and Fred Meyer, checked 2026-08-23.

This article is general information about diaper sizing, not medical advice. Anything about your baby’s birth weight, growth or umbilical cord belongs with your pediatrician, OB or midwife.

Author Profile

Saima Mostari
Saima Mostari
Saima Mostari is the founder and author of BelovedTots. She has raised two young children, Pona and Ruku, and spent years working in child development at Neurosparks, a therapy center that provides Speech Therapy, Occupational Therapy, and ABA Therapy for children with developmental needs.

It was there, watching long therapy sessions get interrupted by leaking, ill-fitting diapers, that she began researching which products actually perform under real-world conditions, not just on the packaging.

She holds a Master's in Psychology and Guidance from the University of Dhaka, and brings a behavioral observation lens to every product she reviews. When she's not testing diapers or writing guides, she's probably negotiating bedtime with a 4-year-old.