It's late September. The stores are full of puffer jackets, and your toddler's pants still fit. Mostly. Now you have to decide what winter clothes sizes to buy for a toddler who will be months older, and noticeably taller, by the time it's actually cold. Below you'll find a size-up table by age, a two-minute fit check, and a plan for buying ahead that doesn't end with a bin of outgrown clothes with the tags still on.

Why the size that fits now won't fit in January

Buying in fall means buying for the future. In much of the country, what you buy in late September gets worn from November into March. By then your child is one to six months older.

Three things make toddler clothes sizing for winter harder than it looks:

• Size steps get wider with age. Baby sizes change every three months (3–6M, 6–9M), then every six months (12M, 18M, 24M), then once a year (2T, 3T, 4T). A 9-month-old can move through two sizes in one winter. A 3-year-old often finishes the season in the same size. If the baby labels are still a puzzle, our plain-English guide to baby clothing sizes explains what each one means.
• Growth doesn't happen on a schedule. Toddlers tend to grow in bursts. You get weeks of no change, then every pair of pants is short at once. No one can tell you when the next burst will land, so a good plan leaves room to be off by a size.
• Labels aren't standard. One brand's 2T can fit like another's 3T. Most brands post a size chart by height and weight, and those numbers are more reliable than the age on the tag.

The size-up table: what to buy based on the size that fits now

Find the size that fits your child well now in the first column, then read across. The age column is only a rough guide, so if your child wears a bigger or smaller size than most kids their age, go by the size, not the age. Not sure what "fits well" means? Run the two-minute fit check in the next section first.

How to read it:

• Baby sizes come labeled two ways. Some brands use a range (12–18M), others a single number (18M). They usually mean the same size, so the table lists both.
• Everyday basics means tops, pants and sweatshirts for the first half of winter. You'll fill in the second half in December.
• Coat and snow gear is sized for February, because it goes over layers and has to last the whole season. For babies, that's usually a bunting or snowsuit for stroller walks.
• If the current size is already snug, start one row down.
• Pajamas are the exception. Snug-fit pajamas should be bought in the size that fits on the day you buy them. More on why below.

These are starting points based on how US size labels step up, not a forecast for your child. When a brand's size chart disagrees with the table, trust the chart.

How to predict your toddler's clothing size: the 2-minute fit check

The best predictor of next month's size is how this month's clothes fit. Put your child in a few current favorites and look for these signs:

• ☐  Sleeves stop above the wrist bone when their arms hang down.
• ☐  Pants show ankle when they sit or squat.
• ☐  Shirts ride up over the belly when they reach overhead.
• ☐  Bodysuit snaps pull, gape or leave red marks.
• ☐  Footed pajamas pull at the shoulders or press on their toes when they stand up straight.
• ☐  Waistbands leave marks, or the neck opening is a wrestle to get over their head.

If two or more are true, your child is already between sizes. Treat the next size up as their current size when you use the table. Our guide on when to switch baby clothes sizes covers more of these signals.

Then take two quick numbers: height with shoes off, and weight. Check them against the size chart for the brands you buy most. If a well-child visit is coming up, use the height and weight from that visit. They'll be more accurate than a tape measure at home.

Which winter pieces to size up (and which to keep true to size)

In short: size up what goes on the outside, keep what goes next to the skin true to size, and be careful with anything your child walks in.

Size up: coats, fleece and sweaters

Outer layers go over other clothes, so extra room is useful. One size up usually still looks right on a toddler, and you can roll the cuffs for the first few weeks.

For snow pants, look for bibs with adjustable straps or hems that can be let down. They grow with your child better than a fixed waist and a fixed length.

Size up carefully: boots and one-piece snowsuits

Boots need room for thick socks, about a thumb's width past the longest toe. Much more than that and a toddler trips. Always try boots on with the socks your child will actually wear.

One-piece snowsuits are hard to buy big for walkers. Extra length in the body bunches at the knees and makes walking clumsy. Once your child is walking, a jacket plus snow bibs is easier to size up, because each piece can fit a little differently.

Keep true to size: snug pajamas, base layers, hats and mittens

Snug-fit pajamas are the one place not to size up. Cotton pajamas sold as "snug-fitting" aren't flame resistant, and their hangtag explains why they need to fit close: loose-fitting sleepwear is more likely to catch fire. Buy the size that fits now, and buy the next size when those get tight.

Long underwear and leggings work best close to the skin, so buy the size that fits now. If your child is at the top of that size, go up one.

Hats and mittens are usually sized by age range. A hat that's too big slides over the eyes, and loose mittens come off in the snow. Buy two pairs of mittens, since one pair is always drying or missing.

Before you buy the big coat: the car seat rule

Puffy coats and snowsuits shouldn't be worn under a car seat harness. The padding flattens in a crash, which leaves the straps too loose. The American Academy of Pediatrics' winter car seat safety tips suggest thin layers in the seat, then a coat or blanket over the buckled harness.

That's a good reason to pair one warm coat for outdoor play with a thinner fleece for everyday car trips, rather than buying two heavy coats.

Buying ahead: shop in two rounds, not one big haul

Buying all of winter at once means betting everything on one guess. Two smaller rounds let you correct course.

Round one: now through October

• Coat and snow gear in the February size from the table.
• Boots, tried on with winter socks.
• One laundry cycle of basics in the "buy now" size. Count the days between loads and add two for spills. If you wash every four days, that's about six tops and six bottoms.

Round two: early December

• Redo the fit check. If your family does a Thanksgiving height check, that fresh mark is a handy round-two number.
• Fill the gaps in whatever size fits then.
• Add a few pieces in the next size if your child is near the top of their current one.

Round two also lands right before the holidays, when grandparents and aunts often send clothes. Tell them the size before they shop. A quick text works:

"If you're thinking about clothes, 3T is the safest size. [Name] is in 2T now, but it probably won't last past January."

"We're set on coats this year. Anything warm in 3T would get worn all winter. For pajamas, ask me first, since they need to fit snugly."

If winter where you live is a few cold weeks in January, skip round two. Buy once, sized for January.

Keep the next size where you can see it

The easiest way to waste a buy-ahead purchase is to forget it. A bag of 3T fleece in the hall closet is how clothes end up outgrown with the tags still on.

Instead, hang the next size in your child's closet, right behind the clothes they wear now:

1. Current size up front, where you reach every morning.
2. Next size right behind it, including this fall's buy-ahead pieces.
3. The size after that at the end of the rod, for hand-me-downs and gifts bought big.

Mark where each size starts, so anyone putting away laundry puts things back in the right section. When the fit check says it's time, pull the outgrown section into a labeled bin for a younger sibling or donation. The next size is already hanging and ready.

We compared five ways to set this up, from bins to labels, in our guide to organizing baby clothes by size.

Our Toddler Closet Dividers fit this setup. The set of four covers 2T to 5T in 1/8-inch etched birch wood, for $24. Hang one at the start of each size, and the current, next and after-next sizes stay separate on a single rod.

Toddler Closet Dividers | Wood Organizing Hangers for Kids

$24.00

View the Toddler Closet Dividers | Wood Organizing Hangers for Kids

If your child is in 18M or 24M now and will cross into T sizes this winter, the Baby & Toddler Closet Divider Bundle covers newborn through 24 months plus 2T to 5T for $48, compared with $52 bought separately.

What to do if you guess wrong

You will guess wrong on something. That's normal, and most misses are easy to fix.

• Too big: Roll sleeves and cuffs, and keep pant hems off the floor so your child doesn't trip. Or hang it in the next-size section, where it will likely fit later in the season. A coat bought big sometimes lasts a second winter.
• Too small by December: That's what round two is for. Leave tags on and keep receipts until a piece is actually in rotation. Check return windows before you buy ahead, since some close before a buy-ahead size ever gets tried on.
• A growth spurt comes early: Move down one row in the table and shop round two a few weeks sooner.
• Almost no growth all fall: The roomier pieces carry into spring. Hold off on round two until the fit check says otherwise.

One more thing: sizing is a closet question, but growth patterns are a pediatrician question. If your child seems to be growing much faster or slower than usual, bring it up at the next well visit.

The short version: run the fit check, find your row, and buy basics for November and the coat for February. Keep pajamas true to size and the next size hanging where you can see it. Then check again in December and buy whatever fits then. A closet sorted this way means fewer cold mornings spent hunting for pants that still fit.

Frequently asked questions