It is a familiar little shopping mystery: you walk into a fitting room certain of your size, try something on, and it feels wrong. In another brand, that same size is perfect. In a third one, it feels far too roomy. It can feel as if your body changed between stores.
Most of the time, your body did not change. The garment did. Once you see that, shopping becomes much less personal and much more practical.
Your size is not a fixed identity: it is a design decision made by each brand.
The pattern matters more than the label
When a brand creates a size, it is not copying a universal truth. It is making choices: what silhouette it wants, how much room to leave at the waist, where the shoulder should sit, what length feels right and who the garment is designed for.
That is why two pairs of trousers with the same size can feel completely different. One may be high-waisted and close through the hip; another may have a relaxed rise, a straighter leg and more ease. The label says the same thing, but the garments speak different languages.
Realistic example
Picture two black blazers. One has a strong shoulder, firm fabric and a fitted cut. The other is fluid, soft and slightly oversized. Both can be a medium, but the first may need sizing up if you want to close it comfortably, while the second may work in your usual size.
Fabric changes the feel
Fabric is the second big reason sizing feels unpredictable. Rigid denim does not forgive like stretch fabric. A structured cotton shirt behaves differently from a soft blouse. A lined skirt may need more room than a knitted one.
Before blaming the size, look at composition. If the garment does not stretch, every centimetre matters. If it has elasticity, you can often choose more precisely. If the fabric is heavy or draped, it can look larger even when the measurements are right.
Fit tells a story too
Words like slim, regular, relaxed and oversized are not decoration. They are clues. A slim top is designed to sit close to the body; an oversized sweatshirt is designed to have room. Trouble starts when we compare both garments as if size were the only variable.
The useful question is not only “what size am I?” It is “how is this garment supposed to fit?” That small shift prevents a surprising number of bad purchases.
Brands design for specific people
Behind every collection there is an idea of a customer. Some brands aim for a youthful, close-fitting silhouette; others prioritise comfort, layers or a more relaxed look. That decision is visible even when the label feels familiar. A brand is not necessarily “sizing badly”; it may be designing for a different proportion, age, use or aesthetic.
The market matters too. An international brand may adapt patterns for different countries, or keep a standard that does not suit every body equally. That is why your own experience is so valuable: what worked, what you returned and which category felt more reliable.
The same brand can change over time
Another common surprise is when a brand that used to work no longer does. Supplier, fabric, trend or creative direction can change. One season favours rigid high-waisted denim; another brings relaxed cuts and wider legs. If you shop from memory without reading the garment, you can miss even with a familiar brand.
This does not mean distrusting everything. It means updating your references. A note such as “this brand works for tailored trousers, but rigid jeans feel tight at the waist” is much more useful than remembering only one size.
Another useful clue
If you always size up in coats from one brand but keep your usual size in dresses, do not save a general conclusion. Save the difference by category. That is the information that actually helps.
SIZES checklist
- Check whether the fit is slim, regular or oversized.
- Compare similar garments, not different categories.
- Save what size works by brand and garment type.
- Watch seasonal changes: collections can vary.
Category matters too
You may wear one size in tops and another in jeans within the same brand, and that does not mean anything is wrong. Tops depend on chest, shoulder and length. Trousers depend on waist, hip, rise and leg length.
That is why one saved size per brand is often not enough. The truly useful memory is by category: dresses, denim, coats, T-shirts, sneakers. That is what makes the next purchase easier.
The key is to stop seeing size as a statement about your body and start seeing it as a feature of the garment. A size that does not work is not a judgement; it is a clue about pattern, fabric or design intention.
When you shop with that mindset, the fitting room becomes less emotional and more technical. You observe, compare, save notes and decide with more calm.
How SIZES helps
With SIZES you can record notes by brand and person: what size worked, in which garment, with which fabric and with how much room. Over time, that information becomes a personal fitting room you carry on your phone.
The next time a size surprises you, you do not need to start from zero. You can check your history, remember what happened last time and shop from a real reference, not a lonely label.