How to measure your chest for clothes

Your chest measurement is the distance around the fullest part of your chest, taken under the arms with the tape level. It decides the size of almost every top, shirt, jacket and coat, so it is worth two minutes and a mirror.

You need a soft tape measure, the tailor's kind (the mètre ruban that Ruban Size is named after). With only a string, mark where it meets and lay it against a ruler.

How to measure your chest, step by step

1. Dress for it. Bare skin or a thin T-shirt. Take off sweaters, jackets and anything with thick seams across the chest. Women: wear the bra you would wear with the garment.
2. Stand naturally. Feet flat, shoulders relaxed, arms down at your sides. Don't puff out your chest or hold your breath.
3. Pass the tape under your arms. Lift your arms just enough to bring the tape around your back, then lower them before you read anything.
4. Find the fullest part. At the front, the tape crosses the fullest part of the chest or bust; at the back, it crosses the shoulder blades.
5. Keep it level. Check from the side in a mirror: the tape should be horizontal all the way round, not riding up your back.
6. Snug, not tight. The tape lies flat on the body without pressing in.
7. Breathe out normally and read. Read where the tape meets its zero end, to the nearest half centimeter or quarter inch, and write down the unit.

If two readings differ, take a third and keep the middle one.

Chest, bust and underbust: three different lines

Size charts use three words that sound alike.

• Chest is the line above: under the arms, around the fullest part. Men's charts use it, and so do many women's tops charts. The Women's tops template in Ruban Size says "Chest: measure around the fullest part of your chest, keeping the tape horizontal."
• Bust follows the same path for most women: "around the fullest part of your bust, tape level", in the Dresses, Swimwear, Plus-size, Petite and Maternity templates.
• Underbust is a different measurement: "snugly around your ribcage, just under the bust." It sets the band of a bra, and swimwear charts often ask for it too. The bra size guide covers it.

So if one women's chart says chest and another says bust, measure once: for most people the number is the same.

Common mistakes

• The tape dips at the back. It adds centimeters without you noticing. Use a mirror or ask someone to check.
• Measuring over clothes. A sweater can add a size on its own.
• Pulling the tape tight to get a smaller number. The ranges of a chart assume a tape that rests on the body.
• Arms up while reading. Raised arms change the shape of the back.
• Using a garment number as a body number. "Pit to pit" across a T-shirt laid flat is half of the garment's chest, and the garment is bigger than the body inside it. More on this in body vs garment measurements.

Body chest or garment chest: reading the chart

The Men's T-shirts and tops template shows both, in two tabs. The body tab lists the chest of the person each size fits; the garment tab lists the T-shirt itself, laid flat and measured across.

A medium T-shirt measures 106 cm around and fits a chest of 96 to 103 cm: the 3 to 10 cm between the two is the ease, the room that lets you move. Compare your body chest with the body tab. If a chart only gives a half chest laid flat, double it and expect it to be larger than you.

What it means for a Shopify store

Shoppers can only measure right if the chart says what it means. Three things help.

• Name the line. "Chest" for a body measurement; "Half chest, laid flat" or "Garment chest" for the garment. A bare "Chest 53" leaves the shopper guessing.
• Put the steps next to the table, not on a separate page, with the same word the table uses.
• Give both units. A US shopper reads inches first, a French one centimeters.

How Ruban Size handles the chest

The Men's T-shirt template and the Women's tops template start with chest rows, a garment tab and a How to measure block. In that block, each step is linked to a measurement: when a shopper points at or taps the chest step, the chest line lights up in the body figure and the chest row lights up in the table. A chart without measuring steps, an imported one for example, gets a short, collapsed How to measure section built from its own measurements.

Find my size asks for the measurements the chart has. On a top, the chest decides and the waist only breaks a tie near a boundary: on the T-shirt template, a 106 cm chest with an 84 cm waist reads "You are between M and L. We suggest L.", with one line per measurement, such as "Chest 106 cm: L, middle of the range". On a dress, where bust, waist and hips all count, it goes by your largest measurement, because a dress that is tight in one place can't be worn. A bust of 98 cm with a waist of 72 cm and hips of 100 cm gets L on the Dresses template, where the bust alone points to L.

When the chart gives the garment's own measurements, Find my size doubles a half chest laid flat and adds room by garment type. For tops, its ease table gives 8.9, 11.6 or 16.7 cm for Snug, Regular and Loose: the midpoints of the Vogue, Butterick and McCall's ease allowances for fitted, semi-fitted and loose tops (3 to 4, 4 1/8 to 5 and 5 1/8 to 8 in). On a chart whose chest row is the half chest laid flat, with the numbers of the T-shirt's garment tab (50, 53, 56, 59 and 62 cm), a 100 cm chest gets M, and L with "Fit I like: Loose". The shopper reads "This chart gives the garment's own measurements: we added room for the fit you chose."

Try it with your own chest:

Questions

Is chest size the same as bust size?

For most women the tape follows the same path: around the fullest part, kept level. Men's charts and many women's tops charts say chest; dresses and swimwear say bust. Underbust is different: it is measured just under the bust and gives the band size of a bra.

Should I measure my chest over a shirt?

Over a thin T-shirt at most. A sweater or a shirt with chest pockets adds enough to move you up a size, and size charts assume a body measurement.

What if my chest and waist point to different sizes?

On shirts, T-shirts and jackets, go by the chest; the waist only matters when you are close to a boundary. On dresses, go by the larger measurement, then read the fit note for what to do between two sizes.

How do I convert my chest from centimeters to inches?

Divide by 2.54. A 100 cm chest is 39.4 in, and a 40 in chest is 101.6 cm.