Suit Size Calculator

How to calculate suit size

Suit sizing starts with seven numbers, chest, trouser waist, jacket length, sleeve length, shoulder width, trouser inseam and height, not with the size you wore last time. Measure your chest at its fullest point, your trouser waist where the waistband sits and your shoulder width across the back, with a soft tape kept level. Then measure sleeve length from the shoulder edge to the wrist bone, jacket length from the base of the collar to the hem, and inseam from the crotch to the hem. The calculator compares chest, trouser waist and shoulder width with broad adult ranges and takes the largest suggested size as the starting point.

Shoulder width then shapes the final choice, because shoulders are the hardest part of a jacket to alter. Two people with the same chest and waist can need different suits if one has broad shoulders and the other has narrow shoulders. The calculator asks for shoulder width so its guidance changes with your number, and it asks for jacket length, sleeve length, inseam and height so the length guidance changes too.

Do not choose suit size from chest alone

Chest alone misses the parts of the suit that fail first. Shoulder width decides whether the seam sits on your shoulder or droops down your arm, trouser waist decides whether the trousers stay up without a belt, and sleeve length decides whether the cuff shows at the wrist. If your shoulders suggest a larger size than your chest, start with the larger size and check the waist separately.

Height matters for length rather than for width. A taller person may need longer sleeves, a longer jacket and a longer inseam even when the size letter is right, while a shorter person may find regular sleeves covering the hands and a regular hem dropping too low. The calculator uses height for that length guidance, and the length letters short, regular and long change the jacket and sleeve without changing the chest.

General suit size chart

The chart below gives broad adult ranges in inches for chest, trouser waist, jacket length, sleeve, shoulder and inseam. Treat these as starting ranges, not as brand sizes. Always check the brand chart for the suit you are buying.

If your measurements fall below XS or above XXL, the chart cannot give you a precise starting size. In that case, use the nearest end of the chart as a rough guide and rely on the brand chart and the stated garment measurements instead.

How shoulder width changes the choice

A shoulder width under 16 inches is narrow, 16 to 21.5 inches covers the broad general range, and over 21.5 inches is broad, as a rough guide. A narrow shoulder needs a narrower cut, a broad shoulder needs a cut made for broader shoulders, and a regular shoulder should fit a regular cut. When the shoulders are wrong, the lapels gap or bow and the sleeves hang at the wrong angle.

Do not try to fix narrow shoulders by sizing down, because that takes width away from the chest and waist as well as from the shoulders. Do not try to fix broad shoulders by sizing up, because that adds width and length you do not need. Pick the cut that matches your shoulders, then pick the size that matches your chest and waist.

Jacket fit: what to check

Check the jacket in this order: shoulders, lapels, button, sleeves, hem. The shoulder seam should sit on your natural shoulder edge, the lapels should lie flat against the chest, and the button should close without pulling into an X shape. The sleeves should end at the wrist bone with a small amount of shirt cuff showing, and the hem should cover your seat and sit level front and back.

The vents at the back should lie flat when you stand and open only when you sit or walk. If a vent flares open while you stand, the jacket is too tight across the seat or hips. A double breasted jacket needs more room to close smoothly, so it usually suits the larger size between sizes.

Trouser fit: what to check

Check the trousers in this order: waist, seat, thigh, break. The waistband should sit at your waist without a belt holding the trousers up, and you should be able to slide two fingers inside it without it gaping at the back. The seat should lie smooth without pull lines or loose folds, and the thigh should have room to walk and sit without the fabric straining.

The hem should meet the shoe with a slight break, a small fold where the fabric touches the top of the shoe. A full break with deep folds looks heavy, while no break at all can look short when you walk. Hemming is a routine alteration, so a trouser that is too long is easier to fix than one that is too short.

How fit and jacket style change suit size

Fit changes how the size feels. A fitted suit should feel close through the chest, waist and thigh with a defined shape, but it should never restrict breathing or sitting. A regular fit skims the body with a little air between fabric and skin. A relaxed fit has clear ease through the chest, waist and leg and is meant to look loose, not sloppy.

Jacket style changes what to check. A single breasted jacket has one column of buttons and a single overlap at the front, so the lapels must lie flat and the button must close without pulling. A double breasted jacket has two columns of buttons and a wider overlap, so it needs more room across the chest and waist to close smoothly, and it usually suits the larger size when you fall between sizes.

Signs a suit is too small

• The button pulls into an X shape and the lapels bow outward.
• The shoulder seam pulls inward and the fabric bunches at the neck.
• The trouser waistband digs in and the pockets gape open.
• The sleeves stop well above the wrist bone.
• You cannot sit or reach forward comfortably in it.

Signs a suit is too large

• The shoulder seam droops past your natural shoulder.
• The lapels float away from the chest.
• The trouser waistband gapes at the back and the seat hangs loose.
• The sleeves cover your hands even with the cuffs in place.
• The hem drops well below mid seat at the back.

How to choose suit size online

Shopping online removes the fitting room, so measurements matter even more. Take fresh measurements, use the calculator for a starting size, then open the brand chart and compare your numbers with the full row for that brand, not just the size letter. If the brand also lists shoulder width and sleeve length, compare those too, especially if you are tall, short, or choosing a double breasted style. Read the fabric and fit notes as well as the chart, because a fitted style already has a close cut built into its sizes.

Common suit sizing mistakes

• Choosing by your usual size letter without checking the brand chart.
• Measuring over thick clothing and then ordering from that number.
• Using chest alone and ignoring shoulder width, trouser waist and inseam.
• Sizing up to fix narrow shoulders, which adds width at the chest and waist too.
• Copying a size letter from a blazer to a suit without checking the cut.