Sizing Up or Down? When to Tailor vs. When to Size Switch
A decision framework for determining whether an ill-fitting piece is worth altering—or if the wrong size compromises the design entirely.
The Real Cost of Getting It Wrong
You've found the coat, the trousers, the dress that ticks every box except one: the fit is slightly off. Before you convince yourself that a tailor can fix anything or that sizing up will solve everything, understand this—some garments are designed with proportions so integral to their identity that altering them destroys what made them special in the first place.
When Tailoring Is the Answer
Certain adjustments respect a garment's architecture. A good tailor can work wonders within specific parameters, and knowing which alterations preserve design intent is half the battle. This tailoring vs sizing guide starts with understanding what's actually fixable.
Safe tailoring moves:
- Shortening sleeves or trouser hems (as long as cuff proportions remain intact)
- Taking in waists on trousers, skirts, and structured dresses
- Narrowing shoulders by up to half an inch on unstructured jackets
- Adjusting side seams on straight-cut garments
- Hemming unlined pieces or those without border details
Consider The Row's tailored trousers. Their clean lines and precise leg width are designed for a specific silhouette, but a tailor can easily adjust the waist or hem length without compromising the overall proportion. Similarly, a Loro Piana cashmere coat with sleeves running long is an easy fix—the shoulder line and body proportions remain untouched.
The key question: does the alteration affect the garment's fundamental proportions? If you're only adjusting length or taking in fabric along existing seams, you're likely in safe territory.
When You Need a Different Size
Some fit issues signal that you're fighting the garment's intended proportions. This is where our tailoring vs sizing guide becomes critical—because no amount of skilled alteration can fix a fundamentally wrong size without compromising the design.
The Shoulder Test
Shoulders are the foundation of fit, particularly in tailored pieces. If shoulder seams don't sit at your natural shoulder point, you're in the wrong size. Period. Moving shoulders more than a fraction requires deconstructing and reconstructing the entire upper portion of a garment—expensive, time-consuming, and rarely successful.
Look at Jil Sander's blazers. Their refined shoulder line is engineered to create a specific silhouette. Trying to alter shoulders by more than a centimeter destroys the balance between lapel, collar, and sleeve head. Size up or down instead.
Pattern Placement and Design Details
Garments with intentional design elements—strategically placed seams, prints, embellishments, or architectural cuts—lose their impact when altered. A Dries Van Noten printed dress with florals positioned to hit at specific body points won't work if you need to take it in significantly. A Comme des Garçons piece with asymmetric proportions can't be "fixed" without erasing the design entirely.
Sizing changes that require moving darts, relocating pockets, or adjusting armhole depth fall into this category. These aren't simple nips and tucks—they're redesigns.
The Fabric Factor
Delicate fabrics, intricate weaves, and certain finishes don't take well to alterations. Visible stitch marks, puckering, or colour changes along old seam lines can occur with:
- Silk charmeuse and other lustrous fabrics
- Heavily textured tweeds and boucles
- Leather and suede
- Garments with special finishes or coatings
If you're considering significant alterations to any of these, reconsider the size entirely.
The Mental Calculation
Before committing to either path, run this tailoring vs sizing guide calculation: quality tailoring in a major city costs £40-150 per alteration. If you need multiple adjustments—hem, waist, sleeves—you're looking at several hundred pounds. Add that to the garment's price. Does the total still feel reasonable? Could you find the right size elsewhere, even if it means waiting?
Also consider timeline. Good tailors are booked weeks in advance. If you need the piece soon, finding the correct size might actually be faster.
Trust Your First Instinct
If you're standing in the fitting room mentally listing three or more alterations needed, that's usually your answer. The right size feels right immediately—maybe not perfect, but fundamentally sound. Everything else is negotiation, and some negotiations aren't worth having.
When in doubt, remember that designers cut patterns with specific proportions in mind. Respecting those proportions, whether through minimal tailoring or finding your true size, means the garment works the way it was intended. And that's always worth the extra effort.
