How Long Do Babies Wear Size 1 Diapers?

Babies grow at different rates, sometimes quickly, and you might wonder how long do babies wear size 1 diapers as you try to plan.

Planning and figuring out how many diapers to buy is tricky. All it takes is one growth spurt, and your baby will be in the next size of diapers.

How are you supposed to take advantage of diaper deals if you can’t figure out how long your baby will be in the size of diapers?

Babies grow at an average rate of 2lbs per month. Based on that statistic, most babies will wear size 1 diapers for up to three months at a time, but there is no perfect science to figure it out.

That’s why we put together this ultimate guide to size 1 diapers so you can figure out how many size 1 diapers you will need for your baby.

And if you love this size 1 diaper guide, then you’ll love these guides on Pampers Baby Dry vs Swaddlers, Pampers Swaddlers Vs Cruisers, Huggies vs Pampers, and diapers vs pullups. Or even our review on Ubbi vs Diaper Genie.


Diaper Sizes Go By Weight

The first thing that parents need to understand is that diaper sizes are determined by weight, so how fast your baby wears a specific diaper size is based on how fast they grow. The length of time your baby stays in one size varies significantly from baby to baby.

Babies all grow at a different rate. Your doctor will tell you a percent range that your baby is in when they get weighed at all of their appointments. Doctors chart all of their patients on a chart that looks like a wave to help track weight. It also lets you know if your baby’s weight is average or not.

Many factors affect your baby’s growth rate; no baby grows the same, even siblings! Some of these factors include:

  • Formula vs. Breastfeeding
  • Family health
  • Length of gestation
  • Birth weight
  • Illnesses

The list goes on and on. That’s why it’s hard to determine how long your baby will wear a specific size of the diaper. Your baby may stay in one size for a few months, then wear the next size for only a few weeks before jumping to the next one.


Recommended Diaper Sizes

Each major (and generic) brand of diapers on the market has its own weight range for diapers. Sometimes, your baby will move out of a size in one diaper brand but not another because they fit differently.

Here are the general diaper sizes for brands.

  • Newborn: 0-10lbs
  • Size 1: 8-14lbs
  • Size 2: 12-18lbs
  • Size 3: 16-26lbs

As you see, the weight overlaps, and other factors go into your baby’s diaper sizing, like if they’re tall or short.

How Long Do Babies Wear Size 1 Diapers?

If you want to buy diapers ahead of time, you might wonder how long do babies wear size one diapers so that you can buy the right amount.

Unfortunately, it differs from baby to baby, so figuring that out is nearly impossible because it varies widely for babies. Some babies begin wearing size one diapers at birth; many babies are in the 8-9lb range and fit well into size one diapers. They might use newborn diapers until the umbilical cord stump falls off, but that only takes a week or two.

Most babies use size 1 diapers within the first month or two after birth. Babies stay in size 1 diapers for two to four months after they start using them.

If your baby started using size one diapers at birth, they should wear this size for two months. If your baby wears size one diapers after newborn diapers, your baby might grow out of size one diapers when he is three to four months old.

On average, babies grow 2lbs per month for the first six months of his or her life. However, some babies grow faster than this or slower than this rate. If your child is 8lbs at birth, they can start using size one diapers at birth and might outgrow size one diapers by the time he is two months old.

If your child is 6lbs at birth, he won’t phase into size one diapers until he is over one month old. Then, it will take another two to three months to outgrow this diaper size.


Should I Buy Newborn Diapers Or Size 1 Diapers?

Parents always wonder whether or not they should buy newborn diapers or size one diapers. If you have babies in the upper weight range of newborn diapers, it’s tempting to skip that size and jump right into size one.

Is that the best choice?

Let’s take a look.

The Difference Between Newborn and Size 1 Diapers

Standard newborn diapers fit babies up to 10lbs, but all diaper brands and all babies are different. Most standard size one diapers fit babies 8-14lbs.

One difference between newborn and size one diapers is that newborn diapers have a cut-out or dip for an umbilical cord stump. It’s not necessarily a feature of every diaper brand because some don’t have it. Still, it’s a nice convenience that stops the diaper from rubbing and pushing the stump off prematurely.

On the other hand, size one diapers don’t have an umbilical cord cut-out, so most parents fold down the front of the diaper to prevent it from rubbing the cord.

If your baby is larger at birth, it’s possible to wear size one diapers in the hospitals. Most hospitals carry them since it’s possible to know what size a baby will be at birth.

The most significant differences between a newborn and a size one diaper are that newborns have an umbilical cord dip and are meant for babies under 10lbs.

Can I Use Size 1 Diapers on a Newborn?

Absolutely! It’s not unusual for babies to weigh 8lbs at birth, and that’s when most size one diapers begin. Parents can use newborn diapers until the cord stump falls out and change up to size one diapers. Another option is to start at size one diapers immediately.

As long as your baby fits appropriately into size one diapers, there is no reason you cannot start with them as a newborn.


Planning How Many Diapers To Buy For Your Baby

It’s possible to buy diapers ahead of time, but it’s an estimate.

So, we recommend that you don’t open diapers ahead of time and keep track of where you buy them. That way, if you do over buy and are looking what to do with extra diapers, you’ll mostly likely have the option to exchange at the store you brought them at for a different size.

Many parents love to buy diapers ahead of time, especially when you find a good sale. So, it can be helpful to figure out how many disposable diapers you’ll need and buy based on the average amount of diaper changes per day for each size.

Using a calculator is the best way to figure out how many diapers you should stockpile. They look at the weight and how many diapers babies tend to use based on their age. It’s best not to buy too many because babies have growth spurts that might cause random growth.


How Do I Know When My Baby Needs A New Diaper Size

After a while, your baby will outgrow a diaper size, and you need to know when it’s time to size up. There are a few signs that it’s time to change sizes.

Frequent Diaper Blowouts

The most common size that your baby needs to move up a diaper size is frequent diaper blowouts. If your diapers all of a sudden start to leak more than before, whether it’s pee or poop, it’s typically the time to size up the diapers.

Hard to Secure Diaper Tags

If you notice that you have to pull harder to secure the diaper tags or that your baby has red marks on his legs or waistline, your baby is ready for the next size up. Sometimes, the diaper tabs start to pop open because they’re stretched too far.

This isn’t comfortable for your baby; it’s time to size up!

Weight is on the High End

Before you buy a new box of diapers, always look at the weight range. If your baby’s weight is on the higher end of their recommended sizing, it’s a good idea to start buying the next size up.

For example, if the weight range is 12-18lbs, and your baby is 17lbs, it’s time to size up.

Frequent Diaper Rashes

Another sign that your baby needs another diaper size is frequent diaper rashes. While applying diaper cream can help with a diaper rash, it is a properly fitting diaper that brings in airflow that helps to avoid diaper rashes.

When your baby wears a too-small diaper, it leads to leaking, redness, and soreness. After you rule out any food-related problems, change the diaper size.

Figuring Out Diaper Sizes

Figuring out how long do babies wear size one diapers is like figuring out how long your baby will wear a specific size of clothes – impossible.

Babies grow and develop at different rates, so one baby might be a slow grower while another takes off like a rocket. Try not to buy too many diapers of one size to avoid ending up with tons of extra diapers.

Final Thoughts On How Many Size 1 Diapers Will I Need

Knowing how many size 1 diapers you need not only ensures that you’re not caught short, but also helps you from overspending on items you don’t need.

We hope this guide has been helpful in deciding how many size 1 diaper you actually need.

And if you’re looking for more great diapering guides, then check out these guides on diaper buying guide, best disposable diapers, best organic baby diapers, and when to start buying diapers when pregnant.