T-Shirt Size Charts: Why Every Brand Measures Differently

What the numbers on a spec chart mean

A maker's size chart lists measurements of the garment, not of the person wearing it. Most blank makers measure the shirt laid flat, so the chest figure is the width from side seam to side seam, not the distance around. Double a flat width to get the circumference: a 20-inch flat chest is a 40-inch shirt.

Three measurements appear on almost every tee chart:

• Body width (chest): straight across, about an inch below the armholes.
• Body length: from the high point of the shoulder (HPS), the spot where the shoulder seam meets the collar, straight down to the hem.
• Sleeve length: either from the shoulder seam to the sleeve hem, or from the center back of the neck to the sleeve hem. A center-back sleeve figure includes half the shoulder width, so it is always the larger number; check which one a chart uses before you compare.

Here is how Gildan lists its 5000, measured flat in inches:

Some fashion and retail labels publish body measurements instead: a range of chest sizes each garment size is meant to fit. Those charts describe the wearer, so their numbers look larger. Mixing up the two kinds of chart is the most common sizing mistake buyers make.

Why a Medium is not the same everywhere

There is no industry-wide size standard for t-shirts. Each maker develops a base pattern for one sample size, then grades it up and down by adding or removing a set amount of width and length at each size step. The base pattern sets the fit; the grading sets how the fit changes across the run.

Compare two common styles, flat, in inches:

The chest widths are almost identical, yet the Comfort Colors 1717 is shorter at every size, by 1 3/8 inches at Small, and its center-back sleeve runs longer (17 3/4 against 16 1/2 at Medium). The grading differs too. The Gildan 5000 adds two inches of width and one inch of length per size, while the 1717 adds about 1 3/8 inches of length per step from Small to XL, so the gap between the two narrows as sizes go up. A customer who wears a Gildan Medium will find the 1717 Medium an inch shorter with a longer sleeve.

Other reasons a Medium varies:

• Fit intent. Retail and fashion fits are cut closer; classic and relaxed fits add room; boxy fits trade length for width. See boxy and oversized fits.
• Unisex vs women's. Unisex charts are generally built on men's proportions. Women's cuts are narrower, with shaped sides and shorter sleeves, and their sizes do not line up one to one with unisex sizes.
• Construction. Side-seamed shirts can be shaped at the waist; tubular bodies are knit as tubes in set widths for each size and run straight.
• Dye and finish. Garment-dyed shirts shrink in the dye bath, so finished sizes vary more from piece to piece. See garment-dyed blanks.

Metric charts and conversions

Blanks made or sold outside the US often list centimeters first, and many charts now give both. One inch is 2.54 cm, so divide centimeters by 2.54 to get inches. WATC Studio's Oversized Boxy Tee, for example, lists its Medium at 61 cm wide and 68.5 cm long, which is 24 by 27 inches. Three habits keep conversions honest:

• Convert before you compare. Rounding a chart to whole inches can hide the half-inch differences that separate two similar styles.
• Check the reference points. A metric chart may still measure flat and from the high point of the shoulder, but some measure length from the back neck seam instead. A small diagram on the chart usually shows which.
• Publish both units yourself. If you sell outside the US, list centimeters next to inches on your own product page so customers never have to convert.

Tolerances

No two shirts come off a sewing line identical. Spec sheets allow a tolerance, a plus-or-minus margin on each measurement, and on body width and length it is usually a fraction of an inch up to about an inch. Some makers print it on the chart: WATC Studio notes that its measurements can vary by 1 to 2 cm. A shirt half an inch off the chart is normally within spec. Two practical effects follow: measure several pieces when you build your own chart, and do not treat a quarter-inch difference between two brands' charts as meaningful.

Shrink after washing

Charts describe new, unwashed shirts. Cotton jersey can shrink in its first hot washes and dryer cycles, and knits usually lose more in length than in width. Champion designed its Reverse Weave fleece around that problem, cutting it on the cross-grain to reduce shrinkage. Preshrunk fabric and garment-dyed shirts shrink less at home, but none are immune to a hot dryer.

For your own size chart, wash and dry a sample of each size the way a customer would, then measure again. If the shirts shrink noticeably, publish post-wash measurements or tell customers plainly to wash cold and hang dry.

How to measure a shirt flat

1. Lay the shirt on a flat table, front up, and smooth it with your hands without stretching it.
2. Body width: measure straight across from side to side, about one inch below the bottom of the armholes.
3. Body length: measure from the high point of the shoulder, beside the collar, straight down to the bottom hem.
4. Sleeve: measure from the shoulder seam along the top fold of the sleeve to the hem. For a center-back sleeve, start at the middle of the back collar.
5. Use a rigid ruler or a tape laid flat, round to the nearest quarter inch, and repeat on two or three shirts of the same size.

Building a size chart for your product page

1. Measure your actual product, printed and finished, not just the maker's chart. Labels, curing heat and pre-washing can move the numbers.
2. List flat measurements in inches and centimeters, and say clearly that they are flat. Add a note to double the chest for the circumference, for customers used to body charts.
3. Add a fit note: classic, relaxed, boxy or oversized, with one plain sentence on how to size. Makers do this on their own pages; Lane Seven, for example, marks its tees true to size and suggests sizing up for a looser fit.
4. Show a model with their height and the size they are wearing.
5. Keep one chart per cut. Unisex, women's and youth styles each need their own.
6. Update the chart when you change blanks. A new style rarely matches the old one, even at the same weight.

For setting charts up in a store, see variants and size charts in Shopify and product pages that sell apparel.

Size charts and the size run

Your chart also shapes what you order. A brand whose tee runs big will sell more Smalls and Mediums than one that runs small, and a boxy cut that customers size down in shifts demand again. Track which sizes sell and which come back as exchanges, and feed that into the next order. How to plan a size run explains how to turn sales into a size run, and blanks vs cut and sew covers the point where a brand writes its own measurements into a tech pack.

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