Oner Active has exploded in popularity — worn by every fitness influencer worth following. But the brand's sizing is genuinely confusing, with multiple fit options per product and a UK size chart that doesn't map cleanly onto standard UK sizing.
The core issue
Oner Active offers some products in "Original Fit" and "Curve Fit" (sometimes called "Sculpt"). These are not the same garment. Original Fit runs narrower in the hip and thigh. Curve Fit has a wider hip-to-thigh measurement and higher rise.
If you order Original Fit by your usual UK size and have hips above 38", you'll almost certainly size up.
Original Fit vs Curve Fit
Original Fit — Designed for a proportional body with hip measurement up to around 12cm larger than waist. If your differential is larger, the hip area will be tight even if the waist is right.
Curve Fit — Designed for a hip-to-waist differential of 14–18cm. This is the better option for pear, hourglass, and fuller-figured women. Runs true to size for most.
Size chart (Original Fit)
| UK size | Oner size | Waist | Hip |
|---|---|---|---|
| 6 | XS | 61 cm | 87 cm |
| 8 | S | 66 cm | 92 cm |
| 10 | M | 71 cm | 97 cm |
| 12 | L | 76 cm | 102 cm |
| 14 | XL | 81 cm | 107 cm |
What the community finds
The most common complaint: ordered Original Fit in usual size, hips fine but waistband rolls down during exercise. This is a fit issue, not a quality issue — the waistband is designed to sit at the natural waist and if the legging is sized for your hips, there's excess at the waist.
The Curve Fit solves this for most women because the proportions are better matched.
Which products are worth it
Seamless Leggings — The core product. Get Curve Fit if your hips-to-waist differential is above 12cm. Quality is genuinely excellent — the fabric is comparable to Lululemon at a lower price.
Flow Shorts — These work well regardless of body type because shorts don't have the waist-hip conflict. True to size.
Sports bras — Size by band, not by cup. Oner's bra sizing doesn't correspond to standard UK bra sizing.
The price question
Oner Active sits at the premium end (£60–£90 for leggings). It's comparable to Gymshark Pro-range but below Lululemon. The quality justifies the price if you can nail the fit — the seamless fabric is genuinely comfortable for all-day wear, not just exercise.