How do I find my t-shirt size from my chest measurement?

Measure around the fullest part of your chest, under your arms, keeping the tape level, then match that figure to a size chart. For men's and unisex tees, a chest of 37 to 40 inches is a medium, 40 to 43 inches is a large, and so on. Women's tees run smaller, so the same chest sits a letter higher. This calculator does the lookup for you and also shows the EU number and the equivalent size in the other gender's chart.

Is a women's medium the same as a men's medium?

No. A women's medium is cut for a smaller chest than a men's medium, typically around 35 to 37 inches versus 37 to 40 inches, and it also has narrower shoulders and a more tapered body. A women's medium is closest to a men's or unisex small in the chest. This is why ordering by letter across genders so often goes wrong, and why the calculator shows the cross-gender equivalent for any chest measurement you enter.

What is the difference between chest circumference and pit-to-pit?

Chest circumference is measured around your body at the fullest part of the chest. Pit-to-pit, or chest width, is measured across a shirt laid flat from one armpit seam to the other, so it covers only the front of the garment. Because a flat measurement spans half the garment, you double it to compare with a body circumference. A 21 inch pit-to-pit shirt corresponds to about a 42 inch garment chest. The calculator handles this doubling when you choose the flat measurement mode.

Should I size up or down in a t-shirt?

Start with the size that matches your chest, then adjust for the fit you want. For a relaxed, oversized, or layering look, go one size up. For a fitted, slim, or muscle-fit tee that follows the body, go one size down. Fabric matters too: a stiff cotton with little stretch fits closer to the chart, while a stretchy blend is more forgiving. When you are between two sizes, sizing up is usually safer for everyday wear since a too-tight tee is uncomfortable across the shoulders.

How do US, UK, and EU t-shirt sizes compare?

US and UK casual tees both use letter sizes, S, M, L, XL, and they line up closely for the same chest. European sizing uses numbers instead, roughly the chest in centimetres divided by two, so a 100 centimetre chest is about an EU 50. Because the systems anchor to the same body measurement, you can convert between them, but the underlying chest each brand assigns to a letter still varies. Always confirm against the specific brand's chart when the fit matters.

Why does the same size fit differently across brands?

Because there is no enforced standard for what a medium or a large must measure, so each brand sets its own chest values, sometimes differing by two inches or more for the same letter. Fast-fashion, premium, and athletic labels often size quite differently, and fits range from slim to relaxed even at the same nominal size. This is why your measured chest is a more reliable guide than your usual letter, and why checking the brand's own size chart against your measurement prevents most online sizing mistakes.

How do I measure my chest for a t-shirt without help?

Stand relaxed and wrap a soft tape measure around the fullest part of your chest, level with your nipples and under your armpits, bringing it around your back to meet at the front. Keep the tape snug but not tight and breathe normally rather than puffing out your chest. Take the reading twice to be sure. If you do not have a soft tape, use a piece of string, mark where it overlaps, and measure the length against a ruler. Accurate measurement matters more than the size you expect.

Can I use a t-shirt I already own to find my size?

Yes, and it is often the most reliable method. Take a t-shirt that fits you exactly the way you like, lay it flat and smooth, and measure pit-to-pit from one underarm seam across to the other. Double that figure and use the flat measurement mode in the calculator to find the equivalent size. This captures your preferred fit, including ease, rather than just your raw body measurement, which is especially useful if you like a particularly relaxed or fitted look.

What chest size is a men's large t-shirt?

A men's or unisex large t-shirt typically fits a chest of about 40 to 43 inches, or roughly 102 to 109 centimetres, though this varies by brand. Below that, a medium covers about 37 to 40 inches, and above it an extra-large covers about 43 to 46 inches. A women's large is cut smaller, for around 37 to 40 inches of bust. These are body-chest ranges; the actual garment is slightly larger to allow movement, which is the built-in ease every t-shirt includes.

Do height and weight determine t-shirt size?

Chest measurement is the primary driver of t-shirt size, not height or weight, because a tee is fitted mainly across the chest and shoulders. Two people of very different heights and weights can wear the same size if their chests match, though height affects how long the shirt looks on the body. Height-and-weight size estimators exist but are far less accurate than a chest measurement, since body shape varies widely at any given height and weight. For the best result, measure your chest and use that.

T-Shirt Size Calculator – Chest to S, M, L, XL Size

T-Shirt Size Calculator

The T-Shirt Size Calculator converts a chest measurement into a letter size from XS to 3XL for a men's, women's, or unisex fit. It returns the chest fit range, the US/UK letter, the EU number, and the cross-gender equivalent that translates the same chest between women's and men's sizing, the question that trips up most shoppers. You can enter a body chest circumference or a well-fitting shirt measured flat pit-to-pit, which the tool doubles, and it includes a full size chart and fit guidance.

What Is the T-Shirt Size Calculator?

The T-Shirt Size Calculator turns a single chest measurement into a letter size from XS to 3XL, for a men's, women's, or unisex fit, and shows the US, UK, and EU equivalents alongside the cross-gender translation. Enter your chest circumference, or the flat pit-to-pit measurement of a shirt that fits you well, and it returns the right size with the chest range it covers. Because t-shirt sizing is built around the chest, as the standard men's t-shirt fit guides set out, a measured chest is a far more reliable guide than the letter you usually reach for.

What makes this calculator stand out is that it tackles the two things that cause the most sizing mistakes. Given that a women's medium is not the same as a men's medium, the tool computes your size in both charts and shows the equivalent, so you can order confidently from a unisex catalogue or translate a partner's size. On top of that, it lets you measure either your body or a favourite shirt laid flat, doubling the flat measurement so the two approaches reconcile. The result is the size to buy, with the context to adjust it for a fitted or relaxed look.

How T-Shirt Sizes Are Worked Out

A t-shirt size is set almost entirely by the chest, because that is where the garment is fitted across the body and shoulders. The calculator matches your chest circumference against a size chart: for men's and unisex tees a chest up to 40 inches is a medium, up to 43 inches a large, and up to 46 inches an extra-large, with each step covering roughly a three-inch band. The garment itself is cut a little larger than your body to allow movement, the built-in ease that every tee includes, so the chart maps body chest to label rather than garment chest to label.

Measuring well is the part that matters most. Wrap a soft tape around the fullest part of your chest, under the arms and level all the way around, snug but not tight, and read it twice. As the detailed t-shirt measurement guides note, breathing normally rather than puffing out your chest keeps the figure honest. If you are also buying a fitted shirt or jacket, the same chest measurement feeds straight into our jacket size calculator.

Men's, Women's, and the Cross-Gender Gap

The single biggest source of t-shirt confusion is treating a letter as if it means the same thing across genders. It does not. Women's tees are cut for a smaller chest at the same letter, along with narrower shoulders and a more tapered body, so a women's medium sits roughly where a men's or unisex small does. The table below shows how the same chest measurement lands on a different letter depending on the chart.

Chest	Men's / Unisex	Women's
34 in (86 cm)	XS	S
36 in (91 cm)	S	M
39 in (99 cm)	M	L
42 in (107 cm)	L	XL

This is exactly the question raised again and again in sizing discussions, such as the widely read threads comparing women's and men's t-shirt sizes. With that in mind, the calculator always shows the equivalent in the other chart, so when a unisex event shirt is the only option, or you are buying a gift, you can convert a known size cleanly instead of guessing. The translation works because both charts anchor to the same chest measurement, just with different letters attached.

Circumference Versus Flat: Two Ways to Measure

There are two honest ways to find your size, and mixing them up causes real errors. The first is your body chest circumference, measured all the way around. The second is a garment measurement: lay a t-shirt that fits you well on a flat surface and measure pit-to-pit, from one underarm seam straight across to the other. Because that flat measurement covers only the front of the shirt, it represents half the garment's chest, so you double it to compare with a body circumference. A 21-inch pit-to-pit corresponds to about a 42-inch garment chest.

The flat method has a quiet advantage: it captures the fit you actually like, ease and all, rather than just your raw body size. If your favourite tee is deliberately relaxed, measuring it flat encodes that preference into the result. The calculator supports both modes and doubles the flat figure for you, which removes the most common piece of bad advice online, comparing a flat shirt width directly against a body chart. Once you have your number, the same measuring discipline carries over to our dress size calculator for fitted styles.

Accuracy and Limitations

The calculator applies standard chest-based size charts consistently, so for an accurate measurement it returns a dependable size and a correct EU conversion and cross-gender equivalent. The men's and unisex chart and the women's chart both reflect common industry ranges, and the doubling logic for flat measurements is geometrically exact. For everyday tees cut to conventional proportions, the recommended size is the one to order.

Even so, t-shirts vary more than almost any other garment. There is no binding standard, so brands assign different chest values to the same letter, and fits range from slim to relaxed, athletic to boxy. Fabric stretch changes how a size feels, and the calculator sizes on the chest alone, which is the dominant factor but not the only one; very broad shoulders or a long torso can call for sizing up independently of chest. Treat the result as a reliable starting point, lean on the cross-gender and flat-measurement features to reconcile what you already own, and confirm against the specific brand's chart whenever the exact fit matters.

The Most Common T-Shirt Sizing Mistake: Ordering by Letter Across Genders or Brands

In my experience the error that produces the most ill-fitting shirts is ordering by the letter someone reports rather than by a chest measurement. A reported medium can mean a women's medium, a men's medium, or one brand's idiosyncratic medium, and those can differ by several inches across the chest. I have seen a single unisex order come back baggy on half the group for exactly this reason. With that in mind, always collect a chest measurement, convert it with the right fit profile, and use the cross-gender panel to reconcile what people think their size is against what the garment will actually be. The letter is a label that shifts with the brand and the gender; the chest measurement is the fixed point that makes every conversion reliable.

T-Shirt Size Calculator