Having a baby is a lot of work. The last thing you need to worry about is preparing for it.

When I was pregnant, the weirdest questions crept into my nesting brain and took root, usually waking me up from a dead sleep in the middle of the night. I remember these being a few – how many onesies will she need? Which type is best? What if she doesn’t fit ANY of them?
Sleepers vs. Snapsuits
First, let’s look at the types of onesies and out there and go over which ones you’ll be reaching for the most.
Snapsuits

Snapsuits (also called one-pieces, rompers or onesies) are great on their own in the summer and excellent layering pieces all year round. We really like to use these as jammies, since we also use a sleep sack and don’t want her legs to get too hot while she sleeps.
The best thing about snapsuits is that they’re available in a bazillion fun designs, so they’re your best bet for finding the perfect thing for cute portraits.
I find myself reaching for these almost every day now since she can wear them with tights, pants or baby legs and I can remove layers as the day gets warmer.
As far as ease of diaper changes go, these are a snap (sorry, had to) since you don’t need to wrangle any flailing limbs.
Sleepers

Footie PJs (a.k.a sleepers or coveralls) are what you’ll reach for most with a brand new baby regardless of the season since it’s just one and done – their whole body will be nice and covered.
My little was born in June and we don’t have AC, so I had stocked up on summer stuff thinking it would be warm enough. I only had 1 little footie jammie that my grandma had sent me, which quickly became our hands-down favorite. We washed as often as possible until we could go out and buy more.
Leave it to Grandma to be the only one who knew – footie jammies are a newborn’s best friend.
To close up a sleeper, you’ll be dealing with a zipper, snaps or sometimes even a tie. While snaps are great for a legless onesie, they’re definitely not the best for footie pjs. The goal is to get diaper changes down to a science, and buttons, ties, and snaps can slow you down. Trust me: zipper every time.
Of course, if you see a sleeper with buttons in a pattern that’s just too cute to handle, it’s not a big deal (especially if they’re very little and haven’t mastered toddler-fu quiet yet. But for your every day jammies, stock up on zipper closes.
Ok, so how many of these should I have?
The real answer is that it depends on what you like, which you’re probably sick of hearing. How on earth can you possibly know what you’ll like until you’re in the thick of it? And it’s not like you can just run out to Target the minute she’s born to shop for her size.
The amount of onesies and footie jammies (sleepers) you’ll need also depends on the weather, and things like cloth diapering. If you’re using cloth diapers (which we do – it’s easier than it sounds), you’ll be doing laundry every day or every other day (again, easier than it sounds), so you won’t need as many clothes.
The amount you’ll need also depends on your stain tolerance. We don’t mind stains, especially on jammies, but every family is different. Plus, I haven’t met a stain I couldn’t get rid of by putting the onesie out in the sun for a few hours. It’s like magic.
While I really do feel that there’s no right or wrong answer, you came here for numbers so I’ll do my best. A lot of moms recommend stashing 3 newborn sized things (remember, babies sometimes come into the world already too big for newborn sizes) and 10 items from all of the other sizes up to a year. 10 seems like a lot to me, especially for the larger sizes. Keep in mind the smaller sizes will be used for much less time since baby’s growth will probably slow down after 6 months.
I’d say rather than stockpiling a horde of random jammies, get a minimal amount of things you really love – you’ll probably never reach for the other stuff.
Get 4 of everything in a variety of sleeve and leg lengths in every size up to 12 months, including a newborn. Be careful that your newborn stuff doesn’t say “premie” – I wound up with a few of those and she never was able to wear them. Make sure you have at least 2-3 sleepers for rotating through the laundry. Other than that, just go with it! You’ll figure out how many you like to have pretty quickly, and you won’t wind up giving away stuff with tags still on.