How to Measure T-Shirt Size: Flat-Lay and Chest Methods

The most reliable way to measure t-shirt size is to lay your best-fitting tee flat, measure it straight across the chest and down the front, and compare those numbers to the brand’s size chart. If you don’t have a favorite tee, wrap a soft tape around the fullest part of your chest and use that number with a chart that lists body measurements. Either way, you only need a tape measure, a flat surface and about five minutes.

Below, we walk through both methods step by step, explain why a Medium at one store is not a Medium at another, and show how to handle the choice between a fitted and a relaxed fit. We also cover hoodies and sweatshirts, since they follow slightly different rules.

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TL;DR

  • Flat-lay a tee you already love, measure chest width seam to seam, and compare it with the garment chart. It is the most reliable method.
  • If you tape your body instead, measure the fullest part of your chest, level and snug, and match it to a chart that lists body measurements, not garment ones.
  • Sizes are not standardized in the U.S., so always check the brand’s own chart rather than trusting the letter on the tag.
  • Decide on fit before size: a relaxed or oversized tee is meant to be bigger than your body, and that is by design.
  • For hoodies and sweatshirts, measure the same way, then think about layering and how roomy you want the look.

Table of Contents

What You Need Before You Start

Keep it simple:

  • A soft, flexible tape measure (the sewing kind, not a metal builder’s tape)
  • A flat, hard surface such as a bed with a board on top, a table or a clean floor
  • A tee that fits the way you want your next one to fit
  • A pen and paper, or your phone’s notes app
  • A mirror or a friend, if you plan to measure your body

Measure in inches if you are shopping from a U.S. brand. Most American size charts list inches, so you will not need to convert anything.

Method 1: Measure a Tee You Already Own (Flat-Lay)

Measuring flat-lay T-shirt chest width

This is the method we recommend first. Instead of guessing where your “fullest part of the chest” is, you let a garment that already fits you do the work. Print-on-demand and apparel guides both treat it as the standard approach: Printful’s guide to measuring a t-shirt describes the same flat-lay points that brands use for their own charts.

Step by step

  1. Pick the right shirt. Choose a tee in a similar cut and fabric weight to the one you want to buy. A thin, fitted baby tee will not tell you much about a heavyweight, boxy one.
  2. Lay it flat. Smooth out wrinkles on a hard surface. Do not stretch the fabric.
  3. Measure chest width. Measure straight across from one side seam to the other, about 1 inch below the armhole. That is the standard point of measure described by Printful. Write down the number.
  4. Measure length. Run the tape from the high point of the shoulder, where the shoulder seam meets the collar, straight down to the bottom hem. Keep the tape vertical. Do not follow the curve of the side, and do not start from the front of the neckline.
  5. Optional: sleeve and shoulder. For sleeve length, measure from the shoulder seam to the sleeve hem. For shoulder width, measure from one shoulder seam to the other across the back.
  6. Compare. Find the size on the brand’s chart whose chest width and length are closest to yours.

The one number people forget to double

Flat-lay chest width is only half of the garment. If a chart you are using lists chest circumference or body measurements, multiply your flat width by two. A tee that measures 20 inches across lies around a 40-inch loop. Printful notes this doubling step for comparing against body-based charts, but remember that a garment always includes some extra room, so the result will usually be larger than your actual body measurement.

Why this method beats the tape on your body

Research on mail-order clothing found that consumers make real errors when measuring their own bodies, and that kind of error is a driver of returns. Different people read “fullest part of the chest” differently. A shirt on a table has no such ambiguity: the seams are right there.

Method 2: Measure Your Body

No favorite tee? Or buying your first tee in a new style? Measure yourself.

How to measure your chest or bust

  1. Stand up straight with your arms relaxed at your sides. Wear a thin, non-padded bra or a fitted top, not a bulky sweater.
  2. Wrap the tape around the fullest part of your chest, across the bust and under the arms, passing over your shoulder blades at the back.
  3. Keep the tape level all the way around. Check in a mirror that it is not dipping at the back.
  4. Keep it snug but not tight. You should be able to slide a finger underneath.
  5. Breathe out normally and read the number.

A useful tip: a friend can do this far more accurately than you can. If you are alone, take it twice and use the larger number if the two differ.

Other measurements worth taking

Measurement Where to take it Why it matters
Chest/bust Fullest part, level around the body Sets the main size
Waist Narrowest part of your torso, usually just above the belly button Matters for fitted or cropped styles
Hips Fullest part of your hips Matters if you like a longer or tucked tee
Shoulder width Across the back, seam point to seam point Matters for drop-shoulder versus set-in sleeves
Torso length Base of the neck to where you want the hem to land Helps you choose between cropped and tunic lengths

Use those numbers only against a chart that is labeled for body measurements. If the chart lists garment measurements (it will often say “flat” or “garment”), your body number needs room added to it.

Body Measurements vs. Garment Measurements

This is the mistake behind a lot of returns. A brand’s spec sheet records the points of measure, how each is taken, the target in every size and the tolerance the factory is allowed. Those are measurements of the finished garment, not of a person.

So, if a chart says a Medium has a 20-inch chest, that is the width of the shirt lying flat, not a promise that a 20-inch chest fits it. Here is how to tell which chart you are looking at:

  • Garment chart: headings such as “chest width,” “body length,” “flat,” or “half chest.” Compare to your flat-lay numbers.
  • Body chart: headings such as “bust,” “waist,” “hip,” or “fits chest.” Compare to your tape-on-body numbers.

For a sense of scale, one published chart for women’s shirts lists a Small at an 18-inch chest width and 25-inch length. That is a garment figure and a general illustration. Your brand’s chart may differ, which brings us to the next point.

Why a Medium Is Not Always a Medium

There is no national sizing rulebook for clothing in the U.S. The Federal Trade Commission requires labels for things like fiber content and country of origin, but sizes themselves are not regulated. As one fashion-law resource puts it, there is no standard for sizing in the United States.

What that means in practice:

  • Each brand builds its sizes from a base pattern and then applies its own increments. That process is called grading, and different brands grade differently, so a size jump of 2 inches at one label might be 1.5 inches at another.
  • Voluntary benchmarks exist, such as ASTM’s women’s sizing standard, but they are guidance, not law. Researchers who compared SizeUSA body-scan data with the ASTM standard found that real body measurements of American women often differ from those benchmarks.
  • Even within one brand, factories work to tolerances. A garment can land a little over or under target and still be within spec. A spec sheet defines the allowed tolerance, so half an inch of difference between two identical tags is not necessarily a defect.

The takeaway is practical: ignore the letter on the tag and use the numbers. When you shop a new brand, find its chart and compare it with the measurements you took from your own favorite tee.

Fit Matters as Much as Size: Understanding Ease

Two tees with the same chest width can look and feel completely different, because of ease, which is the extra fabric built into a garment beyond the body’s measurements so you can move and feel comfortable. Extension resources from New Mexico State University explain that a fitted style has very little ease, while a relaxed or oversized one has more.

A quick way to think about it:

Fit What it looks like How to size
Fitted Close to the body, shows your shape Choose the size nearest your body measurement plus a small allowance
Classic/regular Skims the body with some room Go with your usual size by the chart
Relaxed Loose through the body, often a dropped shoulder Take your usual size for a loose look, or size down for a closer one
Oversized Intentionally big and boxy Take your usual size for the intended look, or size up if you want it truly massive

When a shirt feels “too big,” it is often just doing what it was designed to do. Look for a fit description on the product page before you decide the size is wrong.

How Do You Measure for a Hoodie or Sweatshirt?

The method is the same. Lay your best-fitting hoodie or crewneck flat and measure chest width one inch below the armhole, then body length from the shoulder to the hem. Add two more checks:

  • Sleeve length: from the shoulder seam to the cuff. If your sleeves usually feel short, this number matters.
  • Layering: if you plan to wear a long-sleeve tee under it, take your measurements from a sweatshirt you comfortably wear over one.

Fleece and heavyweight cotton have less stretch than a lightweight jersey tee, so lean toward the size that gives you comfortable room through the chest and shoulders rather than the tightest fit.

From Measuring to Ordering: Our Perspective

We print every design to order, and we have heard the same question from customers again and again: “Should I size up?” Our honest answer is that no size advice beats a number you took yourself.

Our pieces are unisex cuts, and many of the ones our customers love, like the How Great Thou Art Unisex Tee and the In Every Season Unisex Tee, are worn roomy on purpose, the way a lot of moms and young women like their casual tees. So we suggest a simple routine:

  1. Flat-lay the tee or sweatshirt you reach for most.
  2. Write down chest width and length.
  3. Open our size chart and find the size that matches those numbers.
  4. Decide whether you want that same fit, or a looser or closer one, and go one size up or down accordingly.

That is the same flat-lay approach we have described above, and it takes the guesswork out of ordering a piece with a message you want to wear every week. A tee that fits right is one you will actually wear and talk about, and those conversations are the reason we make these designs.

— Ali

Find Your Fit at The Light Blonde

Once you have your numbers, you can shop with confidence. Browse all tees for everyday faith-inspired designs, try the long sleeves for cooler days, or add a layer with the How Great Thou Art Unisex Hoodie. Every design is original, faith-inspired and hand-printed to order.

How Great Thou Art Unisex Hoodie

Common Sizing Mistakes and How to Avoid Them

  • Using a body number against a garment chart. Check the chart’s headings first, as described above.
  • Measuring over thick clothing. Bulky layers add inches. Wear something thin.
  • Pulling the tape tight. A tight tape gives a number that is too small, and the shirt will feel snug.
  • Measuring a stretched-out old tee. A shirt that has been washed hundreds of times may have changed shape. Use one that still fits the way it did when it was new.
  • Comparing different fabrics. Thin rib-knit stretches; heavyweight cotton does not. Use a tee of similar weight to the style you want.
  • Panicking over tiny differences. Factory tolerance exists, and a small variance is a normal part of making clothes.
  • Skipping the fit description. If a product is labeled relaxed or oversized, the size is meant to read larger.

A Worked Example

Say you love a tee that measures 20 inches across the chest and 26 inches long when lying flat.

  1. You check the brand’s garment chart. A Medium shows a 20-inch chest and a 26-inch length. That is your size if you want the same fit.
  2. You want a slightly looser feel this time. You move up one size, which adds chest width and length according to that brand’s grading.
  3. You double the 20-inch width to get 40 inches around, and see that a body measurement chart would list your size as a bit smaller, because the tee includes ease. That is normal.

The numbers above are only an illustration. Always use the actual figures on the chart of the brand you are buying from.

FAQ

How do I determine my t-shirt size in inches?

Lay a tee that fits you flat and measure across the chest, about 1 inch below the armhole, then measure from the shoulder to the hem. Compare those two numbers with the garment chart for the brand you are buying. If you measure your body instead, use a chart that lists body measurements.

Is a 38 t-shirt size M or L?

It depends on the brand and on whether 38 is a body or a garment measurement. Because U.S. sizing is not standardized, one brand may call a 38-inch chest a Medium and another a Large. Check the brand’s own chart and, if you are between sizes, think about whether you want a fitted or relaxed look.

Should I size up in a faith-based graphic tee?

Size up only if you want a looser look than the chart size gives you. Compare your favorite tee’s flat measurements to the chart, then adjust by one size for a closer or roomier fit. Our size chart is the right place to start.

Can I use a men’s or unisex chart for a women’s tee?

Yes, as long as you use the chart for the actual garment you are buying. Unisex pieces are usually cut with more width through the body, so many women choose them for a relaxed look. Measure a tee you already own and match its numbers, rather than relying on the label.

Why does my size change from store to store?

Because brands set their own sizes and grading, and no federal rule fixes what a Medium must measure. Manufacturing tolerance adds a little more variation. Measuring garments instead of trusting tag letters solves most of it.

Sources

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