Generally yes by half-to-full size, especially for end-of-season purchases. Kids grow fast, and tight-fitting clothes are uncomfortable. Exception: pajamas (US flammability standards require snug-fit unless flame-resistant — too-large pajamas are a safety risk for kids under 9). For everyday wear, slightly large is comfortable; significantly large is sloppy. Aim for 1-1.5 size up for items you want to last a season; size down for items the child needs to actually fit now (school uniforms, costumes for events).

What's the difference between 4T and 4?

Same height range but different cut. 4T (Toddler 4): wider seat for diapers, shorter inseam, fuller cut, generally for kids still in diapers or recently potty-trained. 4 (regular kids): slimmer cut, longer inseam, designed for fully potty-trained kids. Most retailers stop selling toddler sizes after 5T; regular kids sizes start at 4 (overlap is intentional — choose based on whether your child is in diapers).

How do European sizes work?

European sizing uses height in cm: 86 = 86 cm tall, 92 = 92 cm tall, etc. Standard intervals: 50, 56, 62, 68, 74, 80, 86, 92, 98, 104, 110, 116, 122, 128, 134, 140, 146, 152, 158, 164. More intuitive than age labels because it's based on actual measurement. To convert: measure child's height in cm, find the closest size up. Most European brands also include US-equivalent labels for export markets.

Why do brands fit so differently?

No standardization in kids' sizing. Same labeled “size 6” varies 1-2 inches across brands. Carter's and OshKosh tend to run generous (size down possibly). Old Navy and H&M tend to run small (size up). Gap, Children's Place are roughly true to label. Patagonia and Hanna Andersson run true to label but quality is higher. When buying a new brand, check reviews for sizing comments and start with one item to test before bulk-buying.

How fast do kids grow?

Highly variable but rough averages: birth to 12 months adds 10 inches and triples weight. 12 months to 2 years adds 4-5 inches. 2 to 5 years adds 2-3 inches per year. 5 to 10 years adds 2 inches per year. 10 to 14 years (puberty growth spurt) adds 3-4 inches per year. After 14, growth slows. So clothes for ages 0-2 last weeks; ages 5-10 may last months to a year if you size up; ages 10-14 last only a season due to growth spurts.

Are hand-me-downs OK?

Yes, and they're economically smart. Kids outgrow clothes long before wearing them out — most secondhand kids' clothing is in excellent condition. Sources: family/friend hand-me-downs (free), consignment chains (Once Upon a Child, Kid to Kid — 50-70% off retail), thrift stores (Goodwill, Salvation Army), Buy Nothing groups (free local exchange). Children's clothing depreciates fast; resale at 30-50% of retail is common. Buying secondhand kids' clothing is one of the highest-leverage household budget cuts available.

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Kids Clothing Size by Age + Height

Find children's clothing size from age, height, and weight — height is the primary signal. Free instant chart for parents, no sign-up or download.

Updated June 2026

Age (years)+ months

HeightUnit

Weight (optional)Unit

Recommended size

Fits approx. 37-39" (94-99 cm), typical weight ~32 lbs.

By height

By age

Weight read

32 lbs

Size	Age	Height (in)	Weight (lbs)
Newborn	0-1 mo	19-21	~8
0-3M	0-3 mo	22-24	~12
3-6M	3-6 mo	24-26	~16
6-12M	6-12 mo	27-30	~20
12-18M	12-18 mo	30-32	~24
18-24M	18-24 mo	32-34	~27
2T	2-3 yr	34-36	~28
3T	3-4 yr	37-39	~32
4T	4-5 yr	40-42	~37
Size 5	5-6 yr	42-45	~45
Size 6	6-7 yr	46-48	~55
Size 7 / Youth XS	7-8 yr	48-52	~60
Size 8 / Youth S	8-9 yr	50-54	~66
Size 10 / Youth M	9-11 yr	54-58	~80
Size 12 / Youth L	11-13 yr	58-62	~100
Size 14 / Youth XL	13-15 yr	61-65	~120
Size 16 / Adult XS	14-16 yr	63-67	~130

Height is the most reliable input — age is a rough proxy. Some brands run small (Zara, H&M) or large (Carter’s, Old Navy); check reviews and the brand’s own chart before buying.

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What it does

Kids' clothing sizes are confusing across multiple dimensions: age-based labels (3M, 6M, 9M, 12M, 18M, 24M, 2T, 3T, 4T, then 4, 5, 6 ... 14, 16) don't match most kids' actual sizes because children grow at vastly different rates. A child's clothing size at 3 years old can be anywhere from 2T to 5T depending on growth percentile and individual variation. Buying by labeled age leads to expensive mistakes. The reliable approach: use HEIGHT first as the primary measurement, weight as a secondary check, and age only as a rough sanity check. Brands publish height-based size charts; align purchases to those, not to your child's birthday-age.

The size guide takes age, height, and (optionally) weight, then outputs recommended size across major US retailers. Standard size progressions: newborn / 0-3M (5-8 lbs, under 23 inches), 3M (8-12 lbs, 23-25 in), 6M (12-16 lbs, 25-26.5 in), 9M (16-19 lbs, 26.5-27.5 in), 12M (19-22 lbs, 27.5-29 in), 18M (22-25 lbs, 29-31 in), 24M / 2T (25-28 lbs, 31-34 in), 3T (28-32 lbs, 34-37 in), 4T (32-37 lbs, 37-40 in), then progressing through 4/5/6/7/8/10/12/14/16 with increasing height and weight ranges.

Practical kid-clothing economics: (1) Babies grow fastest 0-12 months — don't buy ahead more than 3 months because they grow out before wearing. Most parents over-buy 0-3M and have unworn clothes. (2) After age 2, growth slows; you can buy 1 size up for end-of-season purchases. (3) Toddler sizes (2T-5T) and regular kids' sizes (4-7) overlap — confusingly. 4T is for toddlers (still in diapers, larger seat); 4 is for kids (potty-trained, slimmer). Same height, different cut. (4) Major brands run differently: Carter's tends to run large; Old Navy runs small; Gap consistent; H&M runs small (pick a size up). (5) European sizing (in cm: 86, 92, 98, 104, ..., 164) is height-based and more intuitive than US age-based labeling. When in doubt, look at cm-based EU size on a label and convert. (6) Hand-me-downs and consignment shops (Once Upon a Child, Kid-to-Kid) save 50-70% on kids' clothing — which is worth it because kids outgrow clothes quickly regardless.

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How to use it

Enter your child's age (years and months).
Enter their current height in inches or cm.
Optionally add weight for additional sizing precision.
Read recommended size across major US retailers.
Cross-check with the specific brand's size chart for that retailer.

When to use this tool

Buying clothing for a child whose size you're unsure of.
Online ordering when you can't try things on.
Seasonal wardrobe planning — buying ahead for next season.
Gift-giving for nieces, nephews, or friends' kids.
Comparing US and European size charts when shopping internationally.

When not to use it

Specialty kids' sizing (special needs, premature babies, exceptionally tall/short children) — those need brand-specific specialty lines.
Footwear — different sizing math, brand-specific.
Costume/Halloween sizing — those tend to run small; size up.
School uniforms with strict size requirements — refer to school specs directly.

Common use cases

Educational use — demonstrating the underlying concept
Onboarding a colleague who needs the same calculation/conversion
Verifying a number or output before passing it on
Quick use during a typical workday

Frequently asked questions

Should I size up?: Generally yes by half-to-full size, especially for end-of-season purchases. Kids grow fast, and tight-fitting clothes are uncomfortable. Exception: pajamas (US flammability standards require snug-fit unless flame-resistant — too-large pajamas are a safety risk for kids under 9). For everyday wear, slightly large is comfortable; significantly large is sloppy. Aim for 1-1.5 size up for items you want to last a season; size down for items the child needs to actually fit now (school uniforms, costumes for events).
What's the difference between 4T and 4?: Same height range but different cut. 4T (Toddler 4): wider seat for diapers, shorter inseam, fuller cut, generally for kids still in diapers or recently potty-trained. 4 (regular kids): slimmer cut, longer inseam, designed for fully potty-trained kids. Most retailers stop selling toddler sizes after 5T; regular kids sizes start at 4 (overlap is intentional — choose based on whether your child is in diapers).
How do European sizes work?: European sizing uses height in cm: 86 = 86 cm tall, 92 = 92 cm tall, etc. Standard intervals: 50, 56, 62, 68, 74, 80, 86, 92, 98, 104, 110, 116, 122, 128, 134, 140, 146, 152, 158, 164. More intuitive than age labels because it's based on actual measurement. To convert: measure child's height in cm, find the closest size up. Most European brands also include US-equivalent labels for export markets.
Why do brands fit so differently?: No standardization in kids' sizing. Same labeled “size 6” varies 1-2 inches across brands. Carter's and OshKosh tend to run generous (size down possibly). Old Navy and H&M tend to run small (size up). Gap, Children's Place are roughly true to label. Patagonia and Hanna Andersson run true to label but quality is higher. When buying a new brand, check reviews for sizing comments and start with one item to test before bulk-buying.
How fast do kids grow?: Highly variable but rough averages: birth to 12 months adds 10 inches and triples weight. 12 months to 2 years adds 4-5 inches. 2 to 5 years adds 2-3 inches per year. 5 to 10 years adds 2 inches per year. 10 to 14 years (puberty growth spurt) adds 3-4 inches per year. After 14, growth slows. So clothes for ages 0-2 last weeks; ages 5-10 may last months to a year if you size up; ages 10-14 last only a season due to growth spurts.
Are hand-me-downs OK?: Yes, and they're economically smart. Kids outgrow clothes long before wearing them out — most secondhand kids' clothing is in excellent condition. Sources: family/friend hand-me-downs (free), consignment chains (Once Upon a Child, Kid to Kid — 50-70% off retail), thrift stores (Goodwill, Salvation Army), Buy Nothing groups (free local exchange). Children's clothing depreciates fast; resale at 30-50% of retail is common. Buying secondhand kids' clothing is one of the highest-leverage household budget cuts available.

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