Versatility Engine

Every fabric's Formality Level (FL), Formality Flexibility (FF) and Seasonal Range (SR) are ratings established by Lukas Bolz of Thoughtful Style — one canonical rating per cloth, reused everywhere that fabric shows up. The one deliberate exception is shirting flannel, rated separately from tailoring flannel because it's a different product (brushed cotton vs. worsted wool). Each fabric also carries a texture register — napped, coarse, fine, smooth, or sheen. Not everything gets its own rating, though: a pinstripe is a pattern, not a weave, and merino and polyester are fibers, not weaves — none of the three has a formality of its own. Pick whatever actual cloth they're woven into (a pinstripe fresco, a merino saxony, a polyester-blend twill) and rate that instead.

Two pieces are suggested as compatible when their formality levels sit within one point of each other and their texture registers are close. Beyond that baseline, flexibility does the bridging — and the higher of the two pieces' FF ratings is what counts, not the average: a pick-and-pick suit and a royal Oxford shirt sit at the exact same formality level, so their texture gap needs only moderate flexibility (FF 3+) to bridge. A one-level formality gap needs real flexibility (FF 4+) to close, provided the textures already sit close — the way a fine herringbone's FF5 lets it bridge to a sleeker mohair jacket, while a coarse, basketweave pinpoint Oxford still clashes with that same mohair despite a similar formality level. And when a single piece is flexible enough (FF 4+) to genuinely move across registers, it can bridge a two-level formality gap and a two-tier texture gap at once — the reason a flexible worsted like gabardine works equally well against clean indigo denim as against dress trousers, without needing the denim itself to be especially flexible.

This is a suggestion, not a verdict — silhouette, color depth, and pattern scale all shift a real garment's register in ways a rating alone can't capture (a slim Chelsea boot reads dressier than a bulky one; a country-toned gabardine reads more casual than a charcoal one). Color itself isn't numerically scored — it's the fifth, qualitative axis: does the color's own formality agree with the fabric's texture, or fight it. Override any single pairing with the dropdown next to it, and the outfit count recalculates immediately.

Ties and pocket squares don't carry a numeric FL/FF/SR rating, but their texture still maps to a formality band, checked automatically against every shirt, jacket and suit already in your wardrobe: a coarse or napped tie suits FL1–FL3, a medium-textured tie FL2–FL4, and a smooth, silky tie FL4–FL5. Pocket squares get a wider band on the same logic, since only a small amount of fabric actually shows. Like every other pairing, this is a suggestion — override any single one with the dropdown next to it, with a note if you like.

Every fabric also carries a climate tag, warm weather, transitional, cold weather or year-round, read from the weight and character of the cloth as described in the book; a few cloths earn a second season (a heavier fresco also works in the transitional months). Flannel and corduroy are each split into a heavier and a lighter version, because their season depends on weight. Check patterns have no tag of their own: they are woven into whatever base cloth the tailor chooses, so that cloth’s weight decides. These tags describe typical constructions. The actual weight and openness of your piece, and what you layer it with, shift the answer, so treat it as a starting read, not a guarantee.

Pattern, like color, is not scored. Patterns carry no rating of their own: a pin stripe, glen check or windowpane reads at the formality of the base cloth it is woven in, so a pin stripe fresco is rated as a fresco. Any pattern can be recorded on any cloth, so you can describe what you actually own. Recording the pattern simply makes your wardrobe list accurate and lets “What to add next” notice when everything you own is solid. Blazer stripe is offered on jackets only, since it has almost no place in suiting.

If this kind of thinking is useful to you, I write about it weekly. Get registered here → thoughtfulstyle.kit.com/newsletter

The full reasoning behind every rating is in the book → How to Build a High-Performance Wardrobe