Kids Clothing Size Calculator
Kids Clothing Size Calculator
Measure barefoot, standing straight against a wall
Affects waist sizing for pants and jeans
Enter Your Child's Measurements
Enter your child's age, height, or weight to find their clothing size across US, EU, UK, and Australian standards.
US, EU, UK & AU sizes for babies, toddlers, and children
Shopping for children's clothing can feel like solving a puzzle every single time. Sizes vary wildly across brands, countries, and age groups, and a size chart printed in the store rarely matches what actually fits. Whether you are buying for a newborn, a toddler racing through growth spurts, or a school-age child who outgrows jeans every three months, having a reliable reference is essential. This Kids Clothing Size Calculator removes the guesswork by combining your child's current measurements with internationally recognized sizing standards. The calculator supports children from premature newborns all the way through size 18, which covers ages zero to roughly fifteen or sixteen years depending on gender. You can enter your child's age, height, or weight — or all three for the most accurate result — and the tool will instantly show you the correct US size label alongside equivalent EU, UK, and Australian sizes. For older children, you will also see the general letter size (XS through XXL) that many retailers use on their tags. One of the most useful features is the international size conversion. European clothing uses height in centimeters as its primary sizing standard, so a child who is 110 cm tall wears EU size 110 regardless of whether they are four or five years old. UK and Australian sizes tend to be age-based like the US system, but with different label names. All three conversion types are shown simultaneously, which makes it easy to order from international brands without second-guessing. Beyond the basic size lookup, this tool includes a future size predictor. If you want to buy ahead for a holiday, a school year, or a seasonal consignment sale, simply enter a target date and choose your child's growth percentile — from Tiny at the 10th percentile to Very Tall at the 90th percentile. The calculator uses standard pediatric growth rate data to project your child's height and weight at that future date and then recommends the likely clothing size for that time. Shoe sizes are also covered. Enter your child's foot length in inches or centimeters and the tool will return US toddler or youth shoe sizes alongside EU and UK equivalents. Shoe sizing is completely separate from clothing sizing, and many parents overlook how quickly young feet grow — often two or three sizes in a single year for children under five. For parents shopping for pants and jeans specifically, the fit type toggle lets you select Slim, Regular, or Plus (Husky) fit. Retailers like Old Navy, Lands' End, and Gap Kids use these designations to indicate waist adjustments for children who are tall and lean or more compact in build. The tool flags which fit category applies so you know which rack to look at. A belt size is also calculated whenever you provide a waist measurement. The standard formula adds one inch to the waist circumference, which matches how children's belts are sized at most retailers. This calculator treats height as the most reliable input because children of the same age can differ significantly in build. Age-only lookups are provided as a fallback for when you do not have a tape measure handy, but measurement-based results are always more accurate. If your child falls between two size rows, the calculator recommends sizing up to allow for growing room — the same advice you will hear from any experienced children's clothing buyer.
Understanding Kids Clothing Sizes
How Kids Clothing Sizes Work
Children's clothing sizes in the United States are organized into four main categories: Baby (Preemie through 24 months), Toddler (2T through 6T), Little Kids (sizes 4 through 6X), and Big Kids (sizes 7 through 18). Within babies, sizes track closely with age in months. Toddler sizes introduce the 'T' suffix to distinguish them from the overlap with Little Kids sizes around age 4. European (EU) sizes are uniquely height-based — a child's EU size equals their height in centimeters rounded to the nearest standard increment (50, 56, 62, 68, and so on). UK and Australian sizes are primarily age-based but use different label formats. Because sizing is not standardized across brands, always check brand-specific charts when possible and use this calculator as your starting reference point.
How the Size Is Determined
The calculator uses a priority hierarchy to determine the most accurate size. Height takes the highest priority because it correlates most directly with fit across all garment types. When height is provided (in inches or centimeters), the tool looks up the matching row in the size table and returns all international equivalents. Weight is used as a secondary input to confirm or refine the height-based result. If only age is provided, the calculator returns the size corresponding to the midpoint of that age range. For the EU size specifically, the tool calculates the child's height in centimeters and rounds to the nearest EU standard increment (50, 56, 62, 68, 74, 80, 86, 92, 98, 104, 110, 116, 122, 128, 134, 140, 146, 152, and so on).
Why Accurate Sizing Matters
Clothing that fits poorly is more than an aesthetic concern — it affects a child's comfort, mobility, and development. Pants that are too tight restrict movement during play, while overly loose waistbands can cause tripping hazards. For babies and toddlers, clothing that fits correctly reduces the risk of fabric becoming a hazard during sleep or tummy time. On the practical side, buying the right size means fewer returns, less wasted money, and children who are comfortable wearing what you bought. For international online shopping, correct size conversion prevents the most common mistake — ordering a US size 6 when the listing uses EU sizing, which refers to a completely different measurement system.
Limitations and Brand Variation
No online calculator can replace trying clothes on in person or checking a specific brand's size chart. Children's clothing sizing is notoriously inconsistent across manufacturers. A size 5T from Carter's may fit very differently than a size 5T from H&M or Old Navy. Girls' sizing often runs slightly smaller than boys' at the same numeric label, and slim versus regular versus husky cut affects fit independently of the size number. The future size predictor uses generalized CDC growth rate data and should be treated as a planning estimate rather than a precise forecast — individual children grow at highly variable rates influenced by nutrition, genetics, and overall health. For premature infants, sizing should be confirmed with your pediatrician.
Formulas
European children's clothing sizes correspond to the child's height in centimeters, rounded to the nearest standard increment (50, 56, 62, 68, 74, 80, 86, 92, 98, 104, 110, 116, etc.).
Children's belt sizes are calculated by adding one inch to the measured waist circumference, matching standard retail belt sizing.
Estimates a child's height at a future date using CDC average annual growth rates adjusted for the selected growth percentile (10th through 90th).
Reference Tables
US Children's Clothing Size Chart by Height and Weight
| US Size | Age Range | Height (in) | Height (cm) | Weight (lbs) | EU Size |
|---|---|---|---|---|---|
| Preemie | Premature | Up to 17 | Up to 43 | Up to 5 | 44 |
| Newborn | 0–1 months | 17–21 | 43–53 | 5–8 | 50 |
| 0–3M | 0–3 months | 21–24 | 53–61 | 8–12 | 56–62 |
| 3–6M | 3–6 months | 24–27 | 61–69 | 12–16 | 68 |
| 6–9M | 6–9 months | 27–29 | 69–74 | 16–20 | 74 |
| 12M | 9–12 months | 29–31 | 74–79 | 20–24 | 80 |
| 18M | 12–18 months | 31–33 | 79–84 | 24–28 | 86 |
| 24M | 18–24 months | 33–35 | 84–89 | 28–30 | 86–92 |
| 2T | 2 years | 33–36 | 84–92 | 28–32 | 92 |
| 3T | 3 years | 36–39 | 92–99 | 32–36 | 98 |
| 4T | 4 years | 39–42 | 99–107 | 36–40 | 104 |
| 5 | 5 years | 42–45 | 107–114 | 40–46 | 110 |
| 6 | 6 years | 45–48 | 114–122 | 46–53 | 116–122 |
| 7 | 7 years | 48–50 | 122–127 | 53–58 | 122–128 |
| 8 | 8 years | 50–52 | 127–132 | 58–65 | 128–134 |
| 10 | 9–10 years | 52–56 | 132–142 | 65–80 | 140 |
| 12 | 11–12 years | 56–60 | 142–152 | 80–95 | 146–152 |
| 14 | 13–14 years | 60–63 | 152–160 | 95–110 | 158–164 |
| 16 | 15–16 years | 63–66 | 160–168 | 110–125 | 164–170 |
Average Annual Growth Rates by Age
| Age Range | Height Growth (in/year) | Height Growth (cm/year) | Weight Gain (lbs/year) |
|---|---|---|---|
| 0–12 months | 10 | 25 | 14–16 |
| 1–2 years | 5 | 12.5 | 5–6 |
| 2–5 years | 2.5–3 | 6.5–7.5 | 4–5 |
| 5–10 years | 2–2.5 | 5–6 | 5–7 |
| 10–14 years (girls) | 2–3 | 5–7.5 | 8–10 |
| 10–14 years (boys) | 2.5–3.5 | 6–9 | 8–12 |
Worked Examples
Finding the Right Size for a 4-Year-Old
Height = 41 inches → falls in the 39–42 inch range → US Size 4T
Weight = 38 lbs → falls in the 36–40 lbs range → confirms US Size 4T
Convert height to cm: 41 × 2.54 = 104.1 cm
EU Size = nearest standard increment to 104 → EU 104
Buying Ahead for Next School Year
Current height: 46 inches (US Size 6)
Average growth rate for age 5–10: ~2.5 inches/year
Growth in 8 months: 2.5 × (8 ÷ 12) = 1.67 inches
Projected height: 46 + 1.67 = 47.67 inches → falls in 45–48 inch range → still US Size 6, but at the upper end
Size up to allow growing room through the school year
EU to US Size Conversion for Online Shopping
EU 116 = child's height of 116 cm
Convert to inches: 116 ÷ 2.54 = 45.7 inches
45.7 inches falls in the 45–48 inch range → US Size 6
Typical age range: 5–6 years
How to Use This Calculator
Select Gender and Age
Choose Boy or Girl and then toggle between Months or Years. Enter your child's current age. Age alone can return a size estimate, but adding measurements will improve accuracy.
Enter Height and Weight
Enter your child's height (barefoot, standing straight) and optionally their weight. Toggle between Imperial (inches/lbs) and Metric (cm/kg) to match your tape measure. Height is the most reliable input and takes priority in the calculation.
Review All Size Equivalents
The results show your child's US size label, EU size (height-based), UK size, and Australian size simultaneously. The size progression chart shows how long they are likely to stay in the current size and what comes next.
Use the Future Size Predictor
Expand the Future Size Predictor section, pick a target date (for example, next Christmas or the start of the school year), and choose a growth percentile. The calculator projects the likely size at that future date so you can buy ahead with confidence.
Frequently Asked Questions
Why does my child's age suggest one size but their height suggests a different size?
Children grow at very different rates, so age-based sizing is always an approximation. A tall 3-year-old may fit comfortably in a 4T or even a Size 4, while a smaller 3-year-old might still be in 2T. This calculator prioritizes height over age because height correlates much more directly with how a garment actually fits across the torso, arms, and legs. Always use measurement-based results when you have a tape measure available, and treat age-only results as a rough starting point.
What is the difference between US size 4T and US Size 4?
Toddler sizes (2T, 3T, 4T, 5T, 6T) are cut with extra room in the diaper area and a slightly shorter torso. Kids sizes (Size 4, 5, 6) have a leaner cut without that extra seat room. A child who has just been potty trained will usually transition from toddler to kids sizes around age 3 to 4, though the actual fit depends on their build. If you are unsure, buy both and try them on — Size 4T and Size 4 overlap in height and weight ranges but are shaped quite differently in the seat and waist.
How does EU sizing work for children's clothing?
European children's clothing sizes are based on the child's height in centimeters rather than age. The standard EU increments are 50, 56, 62, 68, 74, 80, 86, 92, 98, 104, 110, 116, 122, 128, 134, 140, 146, 152, and so on. So a child who is 104 cm tall wears EU size 104 regardless of whether they are 3 or 5 years old. This makes EU sizing more consistent across brands than the US system. When ordering from European brands like Zara, H&M, or IKEA clothing lines, use your child's height in centimeters as your primary reference.
How accurate is the future size predictor?
The future size predictor uses standard CDC pediatric growth rate data to estimate how much your child will grow by a chosen future date. Average rates are approximately 10 inches per year in the first year of life, 5 inches in the second year, and about 2.5 inches per year from age 2 to 10. Growth percentile adjusts these rates up or down based on whether your child tends to grow faster or slower than average. The result is a planning estimate — useful for buying ahead at consignment sales or ordering holiday gifts — but it cannot account for unexpected growth spurts, illness, or individual variation.
What is Slim vs. Regular vs. Plus (Husky) fit for children?
Many US clothing retailers offer pants in multiple fits to account for children who are lean and tall versus stockier in build. Slim fit (sometimes labeled 'S') has a narrower waist and seat relative to the inseam length. Regular fit is the standard cut. Plus or Husky fit (sometimes labeled 'H' or 'Plus') has a wider waist and seat. The clothing size number itself (such as Size 8 or Size 10) refers to height and general measurements, while the fit type adjusts the waist and seat cut within that size. If your child's pants always gap at the waist or feel tight across the hips, switching fit types will help more than changing the size number.
Why do shoe sizes use a completely different scale from clothing sizes?
Children's shoe sizes are based on foot length measured in inches (US) or centimeters (EU/UK) and use their own separate numbering systems that start from infancy. Toddler sizes (labeled C for Child) run from roughly 0C to 13C, then restart at 1Y (Youth) for larger sizes. EU shoe sizes use the Mondopoint system where the size roughly equals foot length in centimeters multiplied by 1.5 plus 2. Because feet grow rapidly — sometimes two or three sizes per year in toddlers — it is worth re-measuring foot length every two to three months rather than relying on clothing size or age to estimate shoe size.