What size should I get? Predicting your newborn baby's size for a coming home outfit.

June 13, 2016 4 min read 2 Comments

Updated March 2023

One of the most common questions I get from customers here at Cuddle Sleep Dream (my small shop/ handmade baby clothing company) is, "What size should I get?".

Especially for newborns, this is a tricky question!  

You are shopping for a baby who is not even here yet, how can you possibly know what size they need??

We've dressed over 50,000 babies over the past 10 years in our baby boy coming home outfits, so here's how we help moms figure out what size to get for babies that have't arrived yet! 

Why is it so hard to guess what size?

Babies can be 1-12 lbs at birth, (though most are 6-9 lbs) and can grow at all different rates. 

You might try to guess based on an ultrasound, or the fact that "all the babies in your family have been" a certain size, but really we won't know for sure until baby is here.

For a take home outfit, most moms-to-be are looking at sizes Preemie, Newborn, 0-3m, 3m, 0-6m. 

And to make matters more confusing, different brands run wide, skinny, long, etc.

Some quick baby weight facts:

  • Average baby size at birth:
          BOY: 7lb 8 oz / 19.7 in
          GIRL: 7lb 1 oz / 19.4 in
  • 95% of babies are between 5.5-10 lbs
  • Average weight loss: 5-10% in the first week
  • Average weight gain the first month: Most babies regain their birth weight by 2 weeks old. Then they gain about 1 oz/day the first month, meaning they will gain 1.5-2 lbs in their first month.

newborn baby boy size

Brody was 8lb 2oz, 20in, and is wearing size Newborn.

What do we recommend for a coming home outfit? 

We offer our outfits in both size newborn and 3m (which is the same as the ranged size 0-3m).

Generally speaking, if you are shopping for a coming home outfit, we recommend getting a size Newborn. 

Here are 2 reasons why:

1. Baby length is just as important as weight

Size newborn is for babies 5-8 lbs, and up to 21.5", but even most babies up to 9 lbs or so will fit better in size newborn for at least a few days

That's because your newborn's length will also affect their clothing size. The average length of a newborn baby is 19.5" with a normal range of 18-22".  Even babies that weigh a lot can be an average length.

(They also tend to be all scrunched up for a while, so they don't exactly pull and stretch at the length of clothes!)

My first son Jason was 8lb 13oz, 21" and wore size newborn for about a week.

2. Babies lose weight before they gain weight

Did you know that babies lose up to 5-10% of their birth weight in the first week (the lower end if you formula feed and the higher end if you breastfeed)?

It's mostly water weight, which will be regained over the next week or two.  But that initial weight loss can happen very quickly!

A hospital sometimes won't discharge you right away if baby has lost more than 10%, but baby will almost definitely be smaller when you are sent home 1-3 days later than when they were born! 

Roman was 8lb 5oz, 20" and is wearing NB.

There are 3 exceptions to our size Newborn recommendation for take home outfits.

My second son Leo was 8lb 6oz, 20" long and he wore size newborn for a full month.

1. This is not your 1st baby and you know

If this is not your first baby, and your earlier babies were 9+ lb and you know they didn't fit in size Newborn... then you are probably not even reading this blog post because you know 3m is what you'll need! 

big newborn baby

Donovan was 10lbs and is wearing size 3m.

2. Ultrasound says your baby is huge... and mom is worried!

Many customers tell us that their doctor is telling them their baby is going to be gigantic based on the ultrasound.  Keep in mind that ultrasound predictions are often wildly off.  

Personally I would trust a doctor or midwife who is manually feeling your belly with a size prediction, but not an ultrasound.  And still keep the length in mind.  Even heavy babies can be short! 

But if the mom-to-be is is really worried about it, in this case we often recommend ordering both a NB and 3m size - you can always return the one that doesn't fit.

tiny newborn baby size

River was 5lbs 11oz at 5 weeks early and is wearing size NB.

3. You want to use the outfit again for a photoshoot

If you are planning a Newborn photoshoot at 3-4 weeks and want to re-use the outfit, you might want a size 3m. Most newborn shoots happen within 1-2 weeks after birth and a size Newborn should still be fine.  But if you are planning to have it a little later, you may find baby will be more comfortable in a 3m.  

In conclusion

If you are unsure of what size to get, go with Newborn. Size newborn is what works best for most babies, based on our 10 years experience making coming home outfits.

But if you are worried and it makes you feel better - get both! And return the one that doesn't work after baby arrives. 

The only part of our outfits that can't be returned are personalized pieces.  But many of the outfits are only personalized on the hat, and we use the same size hats for both NB and 3m orders.

The non-personalized pieces of our coming home outfits outfits are always able to be exchanged or returned for any reason. 

I hope that helps!

    Ryann Kahn
    Ryann Kahn

    2 Responses


    October 04, 2016

    Definitely helpful for any new moms out there! Looking back at it now I wish I went with both newborn and 3 Month size for his coming home outfit.


    October 03, 2016

    Super Helpful ! Was Unsure Of Correct Size To Have For Brand New Baby.

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