Kids Clothing Size Chart: Age, Height, Weight and Growth Room

When a parent shops for kids clothing online, the first question is rarely “What color?” It is usually “Will this fit my child?” A clear kids clothing size chart answers that before the shopper has to message the shop, wait for a reply, or guess and risk a return.

This guide is for online kids clothing shops on Haravan, Sapo, WooCommerce, Shopify, or a custom site. It covers how to present sizes by age, height and weight, how to include growth room, how regional sizing differences affect your products, and the questions parents actually ask before buying.

Why a kids size chart is not just an adult chart shrunk down

Adult sizing usually assumes a fairly stable body shape. Kids sizing has to handle growth, different body proportions at each age, and the fact that one 4-year-old may be the height of a 5-year-old but the weight of a 3-year-old.

A good kids size chart therefore works from more than one signal:

• Age gives a rough starting point, but it is not reliable on its own.
• Height is often the most useful single measurement because kids’ garments are usually cut by length.
• Weight helps with width, waistbands, chest and seat fit.
• The garment’s own measurements, such as chest width, length and sleeve length, are the final check.

If your chart only says “3Y” or “size 110,” you are asking parents to guess. If it says “fits height 95–105 cm and weight 14–16 kg, garment chest 58 cm,” you have answered most of the questions before they are asked.

The three measurements that actually matter: age, height and weight

When building a kids clothing size chart, the main job is to translate supplier sizes into a language parents understand.

What to put in the chart

A practical chart should include these columns:

• Age range, clearly labeled as approximate.
• Height range in centimeters, and optionally inches for international shoppers.
• Weight range in kilograms, and optionally pounds.
• Your size label, exactly as it appears on the product.
• Garment measurements, such as chest width, length, sleeve length, waistband, or hip.
• A fit note, such as “true to size,” “runs small, size up,” or “generous cut.”

The garment measurements matter most because they remove ambiguity. A parent can measure a well-fitting item at home and compare it with your chart.

Example template

This is a made-up example to show the format, not a universal standard. You should replace every number with your supplier’s actual measurements for the specific product.

Why age alone fails

Age labels are inconsistent between brands. A “5Y” from a Korean supplier may not have the same chest width as a “5” from a US brand. If parents see only age, they will ask things like:

• “My child is 4 but tall for her age, should I buy 5Y?”
• “My child is 5 but slim, will size 5 fall off?”
• “Is size 110 the same as 5 years?”

Your chart should answer the second and third of those directly. Use height and weight ranges, not age alone.

Photo: Kampus Production / Pexels

Growth room: the difference between “fits now” and “will still fit in three months”

Parents often buy kids clothes with extra room so the item lasts longer. This is especially common for coats, school uniforms, dresses and special-occasion outfits.

How to build growth room into the chart

Instead of writing just a single measurement, give a comfortable range. For example:

• “Fits height 92–98 cm” already includes a little growth room.
• “Fits chest 54–58 cm” tells a parent the garment will work over a few months.
• “Buy current size for a regular fit, or one size up for 3–6 months of wear” gives the parent the decision instead of forcing it.

Be careful not to overstate the range. If a garment is described as fitting height 90–110 cm when the actual comfortable range is 95–105 cm, the child may be swimming in it at purchase. A chart with an unrealistically wide range creates more returns, not fewer.

Common wording examples

Good wording:

• “If your child is between sizes, choose the larger size for wear over a season.”
• “This style runs short in the body; size up for a longer fit.”
• “The waistband has adjustable elastic, so the larger size works for slim builds.”

Bad wording:

• “Fits all 4-year-olds.”
• “Size 5 = 5 years.”
• “One size fits 3–6 years” unless the product genuinely does so and the measurements prove it.

Regional sizing differences: Vietnam, Korea, China and US

Kids clothing shops often source from different markets or sell to international customers. A size label alone does not travel well.

What to check by region

How to handle mixed sourcing

If your shop carries products from Vietnamese factories, Korean wholesale suppliers and Chinese marketplaces, do not try to unify them into one chart by age. Instead:

• Create a master chart template with height, weight and garment measurements.
• Fill it in per product or per supplier collection.
• Label the chart with the product name or collection so parents know it is specific.
• Add a note such as “This product follows Korean sizing; please use the height and chest measurements below.”

For international stores, showing both centimeters and inches, and kilograms and pounds, prevents checkout hesitation. For Vietnamese stores selling to local parents, centimeters and kilograms are usually enough, but if you advertise to overseas Vietnamese or export, include both.

Photo: Kampus Production / Pexels

How to build a size chart that answers parents before they ask

The chart itself is only useful if it matches the product and answers real questions.

Step-by-step checklist

1. Get the supplier’s size table for the exact product, not a generic brand table.
2. Measure one sample from each size if you can. Note the chest width, length, sleeve length, shoulder width, waist and hip where relevant.
3. Choose primary columns: height range, weight range, your size label, garment chest and garment length.
4. Add a “how to measure” note or image: height without shoes, chest around the widest part, length from shoulder to hem.
5. Add fit notes for styles that run small, large, short, long, slim or generous.
6. Put the chart in the product description, a tab, or a collapsible block on the product page.

Where parents get confused

Parents read size charts under time pressure. Keep the chart narrow and sort by height. If the chart has ten columns and three different label systems, they will skip it and ask the shop.

A better format is:

• A short line above the chart: “Measure your child’s height and chest, then choose by height first.”
• A table with no more than six columns.
• A note below the chart: “If your child is between sizes, choose the larger size unless the fit note says otherwise.”

Adding the chart to Haravan, Sapo, WooCommerce and Shopify product pages

The easiest method for any platform is to paste an HTML table into the product description area. The next easiest is to use your theme’s custom block or tab feature.

Shopify

• In the product editor, add the size chart as an HTML table in the product description.
• If your theme supports Online Store 2.0 blocks, add a collapsible row or custom liquid block in the product information section.
• Alternatively, create a page called “Size Guide” and link to it from the product description, but a visible table on the product page usually works better.
• Avoid installing an unknown sizing app just to display a table; a simple HTML table is enough.

WooCommerce

• Add the table to the product’s long description using the classic or block editor.
• If you want a separate tab, use a custom product tabs plugin, or your theme’s product data tab options if available.
• For variable products, add size-specific notes in each variation description so the right chart shows with each size.

Haravan

• In the product editor, paste an HTML table into the product description.
• Many Haravan themes let you add a custom HTML block or collapsible section on the product page. Use that if available.
• Since many Vietnamese shoppers use mobile, test the table on a phone. Stack columns or use a simple two-row-per-size layout if the table is too wide.

Sapo

• Similar to Haravan: add the HTML table to the product description or a custom HTML block.
• If your theme supports a separate product tab or content block, place the size chart there, next to the product details.
• Keep the chart above the “Add to cart” button or immediately below it, so parents see it at the decision point.

A consistent product photo style also helps parents judge proportions. If you use invisible mannequin photography for apparel, the garment’s shape is clearer, which works well next to a size chart. See Ghost Mannequin Photography: How to Shoot and Edit Apparel.

What to measure after you publish the chart

A size chart is not a one-time task. You should watch how parents interact with it.

Useful signals to track

• Size-related questions in chat, comments and email. Log the exact wording: “What size for 16 kg?” or “Is 110 the same as 5Y?”
• Return or exchange reasons. If a size is mentioned, note whether the item was too small, too large, too short or too tight.
• Clicks on the size chart link or tab, if your platform or analytics tool can track it.
• Search terms in your store, if your site search supports it.

Worked example without real statistics

For example, if a shop has 200 orders in a month and 30 are returned for size reasons, that is a 15% size-related return rate. The shop can then look at which products caused the most size questions. If the chart says “5Y fits height 104–110 cm” but parents keep saying the sleeves are short, the garment measurements may be wrong or the cut may run small.

Questions parents ask before buying

Use these questions to improve the chart:

• “My child is between sizes, should I size up or down?”
• “Does this run true to size?”
• “My child is tall and slim, which size is better?”
• “What does size 110 mean in age?”
• “Is the waistband adjustable?”
• “How much will this shrink after washing?”
• “Can this fit a nappy if my child is still wearing one?”

Each question can be answered in one or two lines on the product page. For example, under the chart write: “This style runs slim in the chest. If your child is between sizes, choose the larger size.” That sentence can prevent a return.

Common mistakes when presenting kids sizes

Avoid these mistakes in your size chart and product pages:

• Relying on age alone without height, weight or garment measurements.
• Using one generic chart for heterogeneous suppliers, causing wrong fits.
• Hiding the size chart in a separate page with a tiny link.
• Writing “true to size” without explaining true to which market.
• Ignoring growth room, so parents size up too aggressively.
• Listing a size range that is too wide, so nothing fits well at either end.
• Not updating the chart when a supplier changes factories or materials.
• Showing only centimeters to a mostly US audience, or only inches to a Vietnamese audience without equivalents.

A size chart that answers the right questions is a selling tool, not just a support article. It moves the shopper from “Will this fit?” to “I can measure and decide.”

A next step is to let parents judge the look on a real body before buying. Macgi’s virtual try-on widget sits next to “Add to cart” and uses your existing product photos, so a shopper can see themselves wearing the item in about 15–40 seconds. If you run a kids clothing store, you can try Macgi’s free beta at the sign-up page and see whether it fits your product page flow.

FAQ

Should I use age, height or weight as the primary sizing signal?

Use height as the primary signal, supported by weight and garment measurements. Age is only a rough starting point because children of the same age vary widely.

How much growth room should I recommend?

Recommend a comfortable range rather than an extreme one. For most items, “fits height 92–98 cm” is better than “fits 2–4 years.” If parents want extra wear, say: “If between sizes, choose the larger size.”

Do Korean, Chinese and US labels match Vietnamese sizes?

Not reliably. Labels can vary by brand and factory. Always show garment chest, length and sleeve measurements, and note which market the sizing follows.

What if my supplier only gives age labels?

Ask for the garment measurements or measure a sample yourself. If that is not possible, be conservative: state that sizing is approximate and encourage parents to contact you with the child’s height and weight.

How do I add a size chart without installing an app?

Paste an HTML table into the product description or a custom HTML block. On Shopify, WooCommerce, Haravan and Sapo, this works without extra plugins. Test it on mobile because wide tables can become hard to read.

Should the size chart be a table or an image?

A table is better because it is searchable, selectable, and easier to update. If you use an image, also add a text summary or alt text, and keep the font large enough for mobile screens.