When to size up in leggings, and when not to

The default advice — "size up if you're between sizes" — is wrong about half the time. The right answer depends on which measurement put you between sizes, and on a property of the fabric most reviews never mention.

Between-size sits on every legging size chart. The question is which side of it you fall on, and the honest answer is: depends on which body part is over the line, and how much the fabric recovers.

Sizing up to fix a fit problem you don't understand is how a drawer fills up with leggings that almost work.

Size up when

— Your hip is in the upper third of the size range and your waist is in the middle. The waist will be slightly loose. That is fine for activewear. A compressed hip is not — it migrates the waistband down and rolls the front.

— You're shopping for studio work. Pilates, yoga, barre — disciplines where you sit in poses, fold forward, and hold static positions. Slight extra room helps the fabric move with you. Compressed leggings interfere with breath in long holds.

— The fabric is sub-200 gsm. Light fabrics have less recovery. The size that fits at minute one will be loose by minute thirty. A size up gives the fabric somewhere to recover into.

— Your thigh circumference is in the upper third and your hip is in the middle. Same logic as the hip-and-waist case. A legging that grips the thigh too hard creates a barrel shape at the knee and pulls the inseam toward the inner thigh, which causes chafe. (See the legging-to-thigh fit.)

— You're between sizes and pregnant or postpartum. The body is changing in ways the size chart does not anticipate. Comfort over compression for the duration.

Don't size up when

— The waistband rolls. Going up adds slack at the band; rolls get worse. The fix is a different model with a wider, firmer band — usually 7 cm or more. (See the cluster pillar how leggings should fit.)

— You "want compression but it's too tight." That is not a sizing problem. That is a fabric weight problem. A 280 gsm legging in size M will compress less than a 180 gsm legging in size S. Fabric, not size.

— The legging is too short at the ankle. Sizing up will not lengthen the inseam by enough to matter. Brands proportion inseam to size only loosely. The fix is a different cut or a brand that publishes inseam by size.

— You're sizing up to "smooth" the silhouette. A larger legging in a too-thin fabric does not smooth anything. It bags. Look for fabric weight, not size.

— You're sizing up to avoid showing seams or compressed soft tissue at the waistband. Soft tissue at the very top edge of a high-rise band is a body, not a fit problem. Sizing up makes the band loose, which makes it migrate, which moves the soft tissue lower instead of removing it.

Size down when

— The fabric is heavier than 250 gsm and the size you tried fit but did not feel firm. Heavier fabrics have more recovery; a tighter size will not bag and will deliver the compression you bought the legging for.

— The waist is in the upper third and the hip is in the middle. Less common, but real. The hip will be slightly snug; the waist will hold.

— The legging is for running or HIIT. Higher-velocity activities need the band to stay put. A size down on a heavy fabric gives you that without compromising the leg.

When the size chart itself is wrong

Some brands publish size charts based on garment dimensions rather than body dimensions. A "size M" listed as 76–81 cm waist might be the garment's relaxed-state waist measurement, not the body waist it's designed for. A garment-dimension chart will fit roughly two sizes smaller than a body-dimension chart at the same listed numbers.

How to tell:

— If the chart lists "to fit" body measurements with a small range (e.g., 76–80 cm), it's a body chart. Size by your body number plus the rules above.
— If the chart lists "garment measurements" or "flat lay", it's a garment chart. The fabric stretches to fit a body 5 to 15 cm larger than the listed dimension. Skip this brand or contact them for the body chart.

A brand that publishes both is being honest. A brand that publishes neither is asking you to gamble.

What returning the wrong size teaches you

Most online activewear brands return-rate around 30 percent on leggings, primarily on fit. That is the category baseline, not a sign you are doing something wrong. If a legging arrives and the size is wrong, return it and note what was wrong — band rolling, thigh too tight, ankle too short. The next order is informed.

If you keep ordering the same brand and the same size and getting the same fit problem, the brand is not for you. There is no shame in this. Different patterns fit different bodies. Our mid-rise band, fit-tested across the size range is the construction we'd hand-test before deciding either way.

The fit conversation continues in our guide to how leggings should fit.