What size should you knit a baby cardigan? A simple guide for confident making

Knitting for babies is a treat whether for your own grandchildren, neighbours or for friends, but selecting the right size can sometimes feel like a bit of a minefield. If you’ve ever asked yourself what size you should knit a baby cardigan, then join the club!

As we know babies start life all sorts of different weights and lengths and grow at different speeds too! Sizes vary across patterns, and it’s easy to over- or underestimate what will actually fit. 

I hope in this guide, I can help you make confident decisions when it comes to sizing, so your handmade cardigan is both beautiful and practical.

Consider the baby’s age and how fast they grow

Most baby cardigan patterns are sized by age, often in ranges like 0-3 months, 3-6 months, and so on. My Tendu wrap and Cardigan start at a Premature size, Newborn then 0-3m and so on. 

While this offers a helpful starting point, remember that all babies grow at their own pace. If you’re knitting as a gift and don’t know the baby’s exact size, I always think it’s best to size up.

Always be realistic about how quickly you can make the garment. If you are time poor then knit a few sizes bigger so it'll still fit when you hand it over!

Sizing Tip: A slightly bigger cardigan will get more wear. Babies grow into things far quicker than they grow out of them!

Look at the measurements, not just the age range

A good pattern will give you finished measurements for chest circumference and length. I always recommend people look at the ‘finished’ across the chest measurement as a guide; this is more informative than just an age guide. 

Use them to guide your decision, especially if you’re knitting for a baby you can measure or ask about. It’s always easy to add extra length to a baby knit: just adjust the measurement for the ‘knit to armhole’ part of the pattern.

Here’s a rough guide to average chest sizes by age:

• Premature: 31–35cm

• Newborn: 38–40 cm

• 0–3 months: 41–43 cm

• 3–6 months: 44–46 cm

• 6–12 months: 47–49 cm

• 1–2 years: 50–53 cm

Tension Tip: Always check the tension and measure your swatch before starting. A few extra centimetres can make a big difference in fit but may actually be useful in the end!

Think about the season and layering

When deciding what size you should knit a baby cardigan, also think about when it will be worn. A cardigan made in spring may need to be light and snug, while an autumn or winter knit might need room for layering over vests and sleepsuits. 

If you’re knitting for colder months, consider making the next size up to allow for those extra layers.

Choose patterns with room to grow

Many baby cardigan patterns are designed with growth in mind. If possible look for patterns that feature:

• Raglan sleeves or drop shoulders for flexibility

• Extra length in the body or sleeves (which can be rolled up)

• Buttoned or open-front styles that are easy to put on, sweaters unless they have a shoulder button opening can be troublesome to pull over a wriggling babies head!

At Knit One Kits, I offer two intermediate-friendly baby cardigan kits, designed with practical fit and long wear in mind. 

Our baby cardigan knitting kits include soft organic cotton, washable yarns and clear instructions for multiple sizes. When we developed the Tendu Wrap and Cardigan I wanted it to include sizing for premature babies. Having had a shop for many years I could never find enough premature baby patterns to stock and I was always being asked for them. 

 

If in doubt, knit the 6-12 month size

If you’re not sure which size to choose and want your gift to last, 6-12 months is often a safe option. It allows plenty of room for growth and tends to fit babies during the stage when they’re most likely to be out and about. Whether that’s in a pram, a sling, or crawling on the floor.

Aim for wearable, not perfect

Knitting for babies doesn’t need to be exact. In fact, some of the most-loved cardigans are the ones that were slightly too big at first and got worn for months afterwards. 

As long as it’s soft, easy to wear, and made with love, it will be cherished and appreciated.

Ready to start your next baby knit? 

Explore our collection of easy-to-make baby cardigan knitting kits with soft, practical yarns and clear sizing guidance included. Whilst the pattern is easy to follow it is not a beginners pattern unless you have help to hand and are feeling adventurous!

You can also buy both patterns on their own, as they knit to a standard double knit yarn  you can use any standard double knit yarn. It should knit to 22st/28rows per 10cm square - you'll find this info on the ball band or in the yarn description