How many newborn onesies are needed?

As an expecting parent, preparing for the arrival of a newborn baby can be an exciting and overwhelming time. There are many essential items that every newborn requires, with clothing being one of the most basic necessities. For many parents, cotton onesies are a wardrobe staple during the first few months of a baby’s life. But how many newborn onesies should you have on hand? In this article, we will examine the key factors to consider when determining the right number of newborn onesies to purchase in preparation for baby’s arrival.

How Many Onesies Do Babies Need Per Day?

Most experts recommend having at least 5-7 onesies per day for a newborn baby. Here’s a quick breakdown of why babies need so many per day:

Frequent diaper changes: Newborns urinate and have bowel movements very frequently, sometimes as often as every 1-2 hours. Having enough onesies on hand for multiple daily outfit changes is essential.

Spit up and blowouts: It’s practically inevitable that babies will end up with spit up or blowout leaks on their onesies throughout the day. Having extras makes it easy to quickly change baby into a fresh, clean outfit.

Comfort: Onesies provide comfort and ease for diaper changes and nursing/feeding. Having multiple onesies allows parents to keep baby cosy in soft cotton at all times.

Convenience: Having a good stock of onesies means less time spent doing laundry during those hectic newborn days. Extras reduce the need for emergency outfit changes.

So in summary, most baby experts suggest having at least 5 onesies per day, but planning for 7 per day provides a bit more wiggle room for inevitable mess and clothing changes.

How Many Weeks Are in the Newborn Phase?

When it comes to baby clothing sizes, most consider the newborn phase to be the first 3 months of a baby’s life. However, since not all babies are sized the same, it’s sometimes difficult to determine exactly how long your particular newborn will fit into the “newborn” size category. Here are some general newborn size guidelines:

Average newborn phase: 8 – 12 weeks

Premature or small newborns: Up to 16 weeks

Large newborns: As little as 6 – 8 weeks

While the average newborn grows out of that size range by 3 months, some babies might need newborn sized onesies for a bit longer or shorter. Consider your baby’s predicted size and growth rate when estimating how long they’ll need that newborn wardrobe.

As a general rule of thumb, it’s smart to prepare for about 3 months in newborn sizes, but have the next size up ready to go in case your baby has a growth spurt earlier than expected.

How Many Onesies Are Needed for 3 Months?

If we estimate that most babies will need newborn sized onesies for around 12 weeks, and will go through approximately 5-7 onesies per day, we can calculate the total number needed:

– 5 onesies per day x 7 days per week = 35 onesies per week
– 35 onesies per week x 12 weeks = 420 onesies for 3 months

So based on this math, having around 420 newborn onesies on hand should adequately cover the newborn phase of about 3 months while allowing for laundry days.

However, not everyone likes to do laundry every single week. Some parents may prefer to purchase extra onesies to allow for longer intervals between washing.

Here is a breakdown of the estimated newborn onesie requirements for different laundry frequencies:

Laundry Frequency # Onesies Needed
Weekly 420
Every 10 days 525
Every 2 weeks 630

As you can see, the number of onesies needed scales up accordingly if you plan to laundry less often. The takeaway is to purchase enough to comfortably get you through your preferred laundry cycle.

Factors That May Increase Needed Onesies

While the above estimates provide a good starting point, there are some additional factors that may require you to stock up on extra onesies:

Laundry mishaps: Stains, malfunctions, lost socks, and other laundry snafus may decrease your usable onesie inventory.

Seasonal needs: Babies born in colder months may need more onesies to pair with warm pants, sleepers, etc.

Growth spurts: Some babies grow rapidly and might need those larger sizes sooner than expected.

Spit up and blowouts: Some babies have more frequent accidents/messes than average, necessitating more outfit changes.

Multiples: Families with twins, triplets, etc. will need to scale up accordingly.

Childcare situations: Babies in childcare may need extra changes of clothes each day.

Frequency of visitors: More changes of clothes may be needed if baby is being held/passed around frequently.

To account for these potential factors, it’s smart to add at least 10-20% more onesies than your base three month projection. This provides a little extra breathing room.

Newborn Onesie Styles and Features

While stocking up on plenty of basic cotton onesies is key, you may want to look for onesies with extra features or designs that make the frequent diaper changes of newbornhood a bit easier:

Envelope neck: Flap overlaps at neck for quick diaper access.

Mitten cuffs: Folds over hands to prevent scratching.

Footless: Easier for night diaper changes.

Two-way zip: Undoes from top or bottom for diaper changing ease.

Lap shoulder: Broader opening for quick outfit changes.

Snaps: For convenience, avoid onesies with full rows of snaps if possible.

Fun prints: Cute patterns and designs make those multiple daily outfit changes a little more exciting!

Stocking Up on the Right Size

Since sizes vary between baby clothing brands, it’s wise to have your baby’s measurements handy when shopping for onesies. Here are some average newborn size parameters to look for:

Weight: 5-10 lbs
Length: 18-22 inches
Chest circumference: 14-16 inches

Onesies typically come in “preemie,” “newborn,” and “0-3 months” sizes. If your baby is premature or very small, picking up some preemie sizes can help fill the gap until they grow into newborn size.

Check item specifications and size charts to ensure the onesies you select will fit your baby for those crucial first 3 months. Buying too large can be risky, as oversized clothes could pose a safety hazard.

Where to Purchase Affordable Onesies

Thanks to their utilitarian nature, onesies are fortunately one of the more budget-friendly baby items. Here are some of the most affordable places to pick up bulk packs of basic onesies:

Big box stores: Walmart, Target, Costco
Online retailers: Amazon, store websites
Consignment sales: Once Upon a Child, Kid to Kid
Discount/outlet stores: Marshall’s, Old Navy, Gap Factory Store

For the cutest prints and styles, boutique baby clothing retailers also offer great selections but might be pricier. Setting up a baby clothing registry is another potential way to get onesies (and other newborn attire) gifted from friends/family.

Preparing Newborn Onesies for Use

To get those new onesies ready for your little one, be sure to:

Wash with gentle detergent: Use a mild baby laundry soap and skip the fabric softener.

Dry on low: High heat can damage elastic and fade designs.

Check for quality: Examine for loose strings, faulty snaps, etc.

Consider pre-shrinking: Wash and dry on hot once to prevent later shrinkage.

Pro tip: To make putting on a onesie even smoother, fold down the neck and sleeves before placing baby’s limbs through the openings. This prevents extra friction.


Planning for the arrival of a newborn means stocking up on many essentials, with onesies being a key component of any new parent’s preparation list. While each baby’s needs vary slightly, using the guidelines above provides a sensible estimate of how many newborn onesies to have on hand during the first 3 months.

Aim to purchase around 400-600 onesies in varying styles to comfortably get through newbornhood between laundry cycles. And be sure to choose the high-quality, super soft, easy access options that make frequent diaper duty a little more bearable during those hazy early months. With the right supply of onesies, you’ll be able to ensure your newborn is comfortable, clean, and cute at all times!

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