How to create a size chart for clothing is a question every brand meets before its first production order, because a factory cannot make a garment without measurements. A size chart (also called a spec sheet or measurement chart) tells the manufacturer exactly how big each size should be, and it tells your customers which size to buy. In 2026 it is easier than ever, with free spreadsheet templates, purpose-built size chart makers, and AI tools such as Claude and ChatGPT that can draft a graded chart in minutes. This guide covers the five steps, a worked example, the latest tools, and how we use all of it with our own customers.
Body Measurements vs Garment Measurements
Before you start, separate two kinds of chart. A body size chart lists the body measurements each size is designed to fit, such as chest or waist, and it is what customers use to choose a size. A garment spec sheet lists the finished measurements of the garment itself, flat on a table, and it is what the factory works to. A garment is always larger than the body it fits because of ease, so the two charts differ. Most brands need both: the spec sheet for the factory and a simplified body chart for the website.
| Chart | Used By | What It Lists |
|---|---|---|
| Body size chart | Customers and your product pages | Body measurements per size (chest, waist, hip) |
| Garment spec sheet | Your manufacturer | Finished garment measurements, grade rules, and tolerances |
How to Create a Size Chart for Clothing: 5 Steps
Step 1: Determine Your Target Market
Identify the age, gender, and region of your customers, and whether you serve a specialist range such as petite or plus size. Different markets size differently: a US medium is not a European medium, and Asian sizing runs smaller. If you serve plus sizes, see our page for plus size clothing manufacturers in India, because grading above a standard range needs its own rules.
Step 2: Choose a Size Standard
Start from an established reference rather than inventing sizes. ASTM International publishes body measurement tables for women, men, and children, and ISO publishes body measurement standards used across Europe and Asia. Many brands instead copy the measurements of a competitor garment they like, which is practical but should be treated as a starting point to adjust.
Step 3: List the Points of Measure
| Garment | Key Points of Measure |
|---|---|
| T-shirts and tops | Chest width, body length, shoulder width, sleeve length, neck width, sleeve opening, hem width |
| Hoodies and sweatshirts | Chest, body length, shoulder drop, sleeve length, cuff and hem rib width, hood height and width |
| Bottoms and joggers | Waist (relaxed and stretched), hip, front and back rise, thigh, inseam, outseam, leg opening |
| Dresses | Bust, waist, hip, length, strap or sleeve length |
Describe how each point is measured (for example, chest measured one inch below the armhole, flat) so that the factory and your quality team measure the same way.
Step 4: Measure a Good Sample and Grade the Sizes
Take a sample that fits well, measure every point of measure in your base size (usually medium), and repeat on several pieces to confirm consistency. Then grade: add or subtract a fixed increment per size, for example 1 inch on the half-chest between sizes. Grading with fixed rules keeps the fit proportional across the range.
Step 5: Build the Chart and Add Tolerances
Organise the numbers in a table, with sizes across the top and points of measure down the side, and add a tolerance for each measurement, typically half an inch for chest and one inch for length on tops. Tolerances tell the factory how much variation is acceptable and give your inspectors a clear pass or fail line.
Example Spec Sheet: Regular-Fit Cotton T-Shirt
This is an illustrative garment spec sheet in inches, flat, with medium as the base size. Use it as a layout, not as a standard, and adjust it to your own fit.
| Point of Measure | S | M (base) | L | XL | Grade | Tolerance |
|---|---|---|---|---|---|---|
| Chest width (1″ below armhole) | 19 | 20 | 21 | 22 | 1 | ±0.5 |
| Body length (high point shoulder) | 26.5 | 27.5 | 28.5 | 29.5 | 1 | ±1 |
| Shoulder width | 16.5 | 17.5 | 18.5 | 19.5 | 1 | ±0.5 |
| Sleeve length | 8 | 8.5 | 9 | 9.5 | 0.5 | ±0.5 |
| Neck width | 7.5 | 7.75 | 8 | 8.25 | 0.25 | ±0.25 |
How to Make a Size Chart for Clothing With AI Tools
AI assistants have made it much easier to make a size chart for clothing, especially the repetitive parts. Claude, Gemini and ChatGPT can take your base size measurements and grading rules and return a full graded table, in inches and centimetres, with tolerances, in seconds. They are also useful for converting between size systems (US, UK, EU, and Asian), checking that your increments are consistent, and formatting the result for a spreadsheet or a product page. Give the assistant clear inputs, because it can only work from what you provide.
I am making a regular-fit 100% cotton t-shirt. Base size is M. Measurements in inches, flat: half-chest 20, body length 27.5, shoulder 17.5, sleeve length 8.5, neck width 7.75. Grade S, L, and XL using 1 inch per size on chest, length, and shoulder, 0.5 inch on sleeve, and 0.25 inch on neck. Add a tolerance column (half an inch on chest, one inch on length) and show the table in both inches and centimetres.
Treat AI output as a first draft. An assistant can produce plausible numbers that do not match a real garment, so check the chart against a physical sample, measure the sample again, and have your manufacturer’s technical team review it before approving production. Newer tools go further: some AI tech pack generators build a draft spec sheet from a garment photo, which saves time but still needs a technical review of the graded measurements and construction notes.
Free and Low-Cost Tools for Making a Size Chart
| Tool | Best For | Cost Note |
|---|---|---|
| Google Sheets or Excel | Factory spec sheets with grade formulas and tolerances | Free |
| Claude or ChatGPT | Drafting, grading, converting units and size systems | Free tiers available |
| Canva | Branded size guides for your website and packaging | Free templates |
| Sizely | Interactive size charts with an inches and centimetres toggle, across hundreds of garment designs, for your store or marketplace listings | Free plan; paid plans from about $14 a month |
| Techpack Builder | Full tech packs with spec tables on Mac or Windows | Free desktop download |
| Techpacker | Team collaboration and a reusable spec library | Paid, per user |
| SmartSize and similar Shopify apps | Size charts and fit finders on your store, some with AI image-to-table tools | Free plans, then paid |
| AI tech pack generators | First-draft spec sheets from a garment photo, such as Adstronaut AI and Genpire | Free tiers or credit-based |
Prices and plans change often, so check each tool’s current terms. The old version of this page recommended Gravit Designer, which has since been rebranded, so we have removed it.
Our Experience: AI, Spec Sheets, and Serious Buyers
We use these same tools with customers. When a buyer does not have a measurement chart, we do not turn them away: we ask for a reference garment or its measurements, then use AI tools such as Claude and ChatGPT to draft a graded chart that we check against the sample. Asking for a spec sheet early is also a simple way to gauge how serious a customer is. A buyer who has thought through their measurements has usually thought through the product, while a buyer with no chart and no reference garment is often earlier in the process. Neither is a problem, but it tells us how much guidance the order will need. Our guide on how to choose a clothing manufacturer explains why a correct measurement spec is one of the three things that matter most, alongside correct designs and a decent volume.
Size Chart, Tech Pack, and Mockup: How They Fit Together
A size chart is one part of the package a factory needs. The tech pack combines your size chart with flat sketches, fabric, trims, and construction details, and our guide on what to send to a clothing manufacturer lists everything to include. A mockup shows the look and print placement, and our guide on how to send mockups to a manufacturer explains how a mockup differs from a tech pack. Once the chart is ready, a sample confirms the fit, and our page on free sample clothing manufacturers explains how sampling costs work. Tolerances in your chart are what inspectors check during production, as our guide to finding high quality clothing manufacturers shows.
Common Size Chart Mistakes to Avoid
| Mistake | Fix |
|---|---|
| Mixing body and garment measurements | Keep a separate spec sheet for the factory and a body chart for customers |
| No tolerances | Add a plus-or-minus value for every point of measure |
| Unclear measuring method | Describe where and how each point is measured |
| Uneven grading | Use fixed increments and check the whole size run |
| Trusting AI output blindly | Check against a physical sample before bulk |
The Synerg, Tirupur, India
If you do not have a measurement chart yet, send us a reference garment or its measurements and our team will help you build a graded spec sheet for your first design. We are a Tirupur-based clothing manufacturer with our own factory of 100 sewing machines, knit orders from 300 pieces per colour per style, 75 to 90 days from purchase order to shipment, and every order inspected to AQL 2.5.
Our recommendation
Build your garment spec sheet in a spreadsheet, draft and grade it with an AI assistant, and then confirm every measurement on a physical sample. Add tolerances, describe how each point is measured, and send the chart with your tech pack so the factory and your inspectors work to the same numbers.
Frequently Asked Questions
How to create a size chart for clothing?
Define your target market, choose a size standard, list the points of measure, measure a good sample in your base size, grade the other sizes with fixed increments, and add tolerances. Build it in a spreadsheet or size chart tool and check it against a sample.
How to make a size chart for clothing with AI?
Give Claude or ChatGPT your base size measurements and grading increments, ask for a graded table with tolerances in inches and centimetres, then verify the result against a physical sample before production.
What is the difference between a size chart and a spec sheet?
A size chart usually shows body measurements for customers, while a spec sheet lists finished garment measurements, grade rules, and tolerances for the factory. Most brands need both.
What is a good free tool to make a size chart?
Google Sheets or Excel for factory spec sheets, Canva for branded size guides, Techpack Builder for full tech packs, and Sizely or Shopify apps for interactive charts on your store.
Do I need a size chart before I contact a clothing manufacturer?
It helps a great deal, because a measurement spec lets the factory quote and sample accurately. If you do not have one, send a reference garment or measurements and ask the manufacturer to help you build it.
About the Author: Karthik Shan
Karthik Shan is the founder and CEO of The Synerg, with 20+ years in the Tirupur textile hub. He publishes practical playbooks for brands on fabric GSM, costing (CM/CMT), AQL quality standards, and export-ready production.