Suit Jacket Size Guide
The architecture of a suit jacket is built upon three pillars: the shoulder, the chest, and the waist. Understanding the precise relationship between these measurements — and how they translate across Italian, British, and American sizing conventions — is essential for any gentleman investing in luxury tailoring. Our calculator determines your exact size, your jacket length (Short, Regular, or Long), and your “drop” — the critical ratio between chest and waist that governs whether a ready-to-wear jacket will harmonize with your physique.
Your Build
Height determines your jacket length — Short, Regular, or Long.
Suit Sizing — Frequently Asked Questions
What size suit am I?
Your suit size is determined primarily by your chest circumference. Measure the fullest part of your chest and round to the nearest even number. This is your US/UK size. Add 10 for your Italian (IT/EU) size. For example, a 40-inch chest corresponds to a US 40 or an Italian 50.
How should a suit jacket fit in the shoulders?
The shoulder seam should sit precisely at the edge of your shoulder bone — the acromion. If the seam falls onto your upper arm, the jacket is too large. If it pulls inward from the bone, it is too small. This is the single most critical fit point because shoulder alterations are extremely expensive and often compromise the garment's structure.
What is Drop 6 in suit sizing?
Drop 6 means the trouser waist is 6 inches smaller than the jacket chest measurement. This is the standard proportion used by most luxury houses like Canali, Isaia, and Brioni. An athletic build with broader chest and narrower waist may need Drop 7 or 8, while a comfort build may require Drop 4 or 5.
Should I buy a slim fit or regular fit suit?
This depends on your build and the occasion. A slim, close-to-body fit — favoured by Neapolitan tailors — works best for lean builds and contemporary settings. A classic regular fit in the Savile Row tradition provides room for layering and is more versatile across formal occasions. When in doubt, buy for the shoulder fit and have a tailor adjust the torso.