Activewear and compression sizing: tight on purpose

Activewear and compression garments fit differently from everyday clothes because they are meant to be smaller than the body. A legging, a cycling jersey or a sports bra stretches over you and holds; that hold is the point. So a shopper who takes "her usual M" can find it tight, and that can be exactly right.

Size these garments by the brand's own measurements, then read the fit note. It tells you which way to go when you're between two sizes, and the answer depends on the product.

Negative ease, in numbers

Ease is the difference between a garment's measurement and the body inside it. A regular woven top has about 11.6 cm of ease at the chest in Ruban Size's ease table. Knits for activewear, swimwear and underwear go the other way: the table gives them -2 cm for a snug fit, 0 for regular and 2 cm for loose, before stretch.

Then stretch takes a share of the body measurement off the garment measurement: 8% for activewear, 10% for swimwear, 6% for underwear and 5% for jersey tops. For a shopper with 100 cm hips, the leggings she needs measure, around the hips:

The same shopper needs a 90 cm swimsuit at a regular fit, since swim fabric takes 10%. Garments 8 to 10 cm smaller than her hips are the ones that fit. How much ease clothes need has the whole table, woven garments included.

How close each kind of garment sits

Ruban Size's sport and swim templates each come with a fit scale and a note that says how close the cut is and what to do about it:

Two directions show up. For leggings and cycling kit, a size up trades compression for comfort. For sports bras, the template's own text says "Between two sizes, take the smaller one for more support": a looser band moves and stops supporting. Both are right for their products, which is why one rule for a whole sport section fails.

Medical compression garments are a separate case: they are sized to the maker's own measuring points and levels, and only their chart applies.

What to measure

• Leggings and yoga pants: waist and hips, plus inseam for length. In the leggings template, the hips step 5 to 6.5 cm a size and the inseam 1 cm.
• Cycling and compression tops and shorts: chest, waist, hips and height. The cycling template's height ranges overlap (166 to 167 cm is in both XS and S), so a rider at the edge gets to choose by girth.
• Sports bras: underbust first, then bust. The sports bras template sizes XS to XL from the underbust, with the bra sizes each one covers (an M is 34C to 36B).
• Swimwear: bust, underbust, waist and hips. Find my size gives the hips the most weight on a swimwear chart.

Measure on the skin or over thin underwear, tape snug but not pulled. A loose measurement on a garment made to compress gives a size too big.

Try the cycling chart with a chest and a height:

Between two sizes

The fit note decides, and it should say which way and why:

1. For support, the smaller one. Sports bras, and any piece where the hold is the point.
2. For comfort over long hours, the larger one. Leggings for everyday wear, cycling kit for a relaxed ride, swimwear.
3. When the measurements disagree, the one that matters most. Hips for leggings and swimsuits, underbust for sports bras.

A store can write its own version of these on each chart. Fit notes that help has the pattern: name the cut, then the action with its condition.

How Ruban Size handles it

It recognizes the product. Find my size reads the chart's words: legging, yoga, activewear, sport, compression, cycling, running, gym or fitness make it an activewear chart, with waist, hips, chest and bust as the measurements that count. Swimwear and underwear are categories of their own, with their own stretch. A sports bras chart is read as a bra chart: underbust first, then bust, where too loose fails as much as too tight.

Body charts already count the stretch. On a chart of body measurements, like the leggings template, the ranges are the bodies each size fits, stretch included. "Fit I like" moves the shopper's measurement by 1 cm either way, half the knit row's gap. Stretch lets a measurement go a quarter of a size step past the top of a range before it counts as too tight: with a single measurement the chart's boundary holds, and when waist and hips disagree, the smaller size can win. Turn on Stretch fabric yourself in the chart's Fit and Find my size tab, and a shopper right at a boundary can get the smaller size.

Garment charts get the numbers above. When a chart gives the garment's own measurements, laid flat or around, Find my size adds the knit ease and takes off the stretch share before comparing, and the answer says the chart gives the garment's own measurements.

The fit scale is part of the answer. One step small moves the shopper's target up by a fifth of a size step; two steps, by 0.55 of a step. On the cycling chart, whose sizes step 6 cm, "Runs small" is a 3.3 cm move. The answer adds "This item runs small: we took it into account." The sports bras template comes set one step small, with its support note, ready to adjust to your own measurements.

Questions

Should activewear be tight?

Close, yes: activewear is cut to sit close, often smaller than the body, so it holds and doesn't shift. It should not restrict breathing or leave deep marks; if it does, take the next size.

Should I size up or down in compression wear?

Down, or true to the chart, for more support; up for comfort. Follow the brand's fit note: leggings and cycling templates in Ruban Size say one size up for less compression, sports bras say the smaller size for more support.

Do sports bras fit like regular bras?

They go by the same two measurements, underbust and bust, but many come in letter sizes that each cover several bra sizes: in Ruban Size's template, an M covers 34C to 36B. Choose by underbust first, then check the bust.

Why are my leggings smaller than my hips?

Because the fabric stretches. A legging for 100 cm hips can measure around 92 cm before it's worn, and that negative ease is what keeps it in place.