Should the bottom button of a waistcoat be unbuttoned?

Yes — convention says always leave the bottom button undone. Originated when King Edward VII couldn't fasten his bottom button comfortably; the rule stuck. Modern vests are cut to be worn with bottom button open — fastening it pulls the fabric awkwardly.

Can a waistcoat be worn without a jacket?

Yes — popular for semi-formal occasions. Without a jacket, the vest's hem visibility doesn't matter. With a jacket, the vest must NOT show below the jacket hem. Vest length is critical when wearing as 3-piece suit.

What's the difference between a vest and a waistcoat?

Same garment. 'Waistcoat' is the British/formal term; 'vest' is the American term. Both refer to the sleeveless upper garment with buttons in the front and a back made of contrasting (often satin or rayon) fabric.

What size vest if I'm a 40R suit?

A 40R vest typically fits a 40-inch chest with standard front length. Vests use the same chest sizing as suits. If buying a vest separately from the suit (i.e., adding a vest to an off-the-rack 2-piece), match by chest size and check front length matches your torso.

Do I need a vest tailored?

Often yes. Vests are slim by design and most off-the-rack vests need 1-2 inches taken in at the waist back. Vest back panels have an adjustable buckle/cinch in many cases — start with that before tailoring. Front length often needs adjustment if you're between standard heights.

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How to measure May 15, 2026 4 min read

How to Measure for a Waistcoat (Vest)

Three numbers — chest, waist, front length. Plus the rule that vests must NEVER show below the jacket hem. Here's how to measure for a 3-piece-suit waistcoat.

The Three Measurements

Measurement	Where	Notes
Chest	Fullest, over dress shirt	Vests are worn over shirts
Waist	Natural waist (narrowest)	Vests are slim — don't suck in
Front length	Highest shoulder to vest hem	Hem must NOT show below jacket

The 'Don't Show Below Jacket' Rule

Vest must not be visible under jacket hem

A 3-piece suit's golden rule: when the jacket is closed (or even open), the vest hem should NEVER peek below the jacket. Front length is what controls this — too long = visible below jacket = looks wrong.

Suit jacket length	Vest front length
30" jacket	21-22" vest
31" jacket	22-23" vest
32" jacket	23-24" vest
33" jacket	24-25" vest
34" jacket	25-26" vest

Vest Adjustments You Should Know

Back cinch buckle: almost all vests have a cinch in the back. Adjust this BEFORE tailoring waist.

Tailored waist take-in: ~1-2" at the side seams. Cheap and standard alteration.

Front length shortening: hem can be raised 0.5-1\" if vest is too long.

Lapel addition: some tailors can add lapels to a plain vest for $50-100.

Common Mistakes

Buying vest in casual size

Casual sizing assumes loose fit. Vests are slim — buy true chest size.

Vest visible below jacket

Front length too long. Hem the vest or get one with shorter cut.

Buttoning the bottom button

Convention says always unbutton. Vest is cut to be worn that way.

Skipping the back cinch adjustment

Try the cinch first before tailoring. Free fix for waist looseness.

FAQs

How should a waistcoat fit?

Slim and snug, hugs waist, no excess fabric.

Bottom button buttoned or not?

Always unbuttoned. Convention.

Vest without a jacket?

Yes for semi-formal. Hem visibility doesn't matter without jacket.

Vest vs waistcoat?

Same garment. UK = waistcoat, US = vest.

Vest size for 40R suit?

40R chest. Match front length to torso.

Need vest tailored?

Often yes. Try back cinch first.

Three Numbers, One Right Vest

For tuxedo + suit reference see tuxedo guide and men's suit chart.

Selling 3-piece suits on Shopify?

Tailor Size Guide adds vest front length matching to every 3-piece listing — so customers never get a vest that shows below their jacket.

Install the Shopify app Read the docs