Trainers aren't the only thing worth checking before you order — tracksuits, jackets and tees can vary just as much between brands. Here's a full breakdown of standard UK clothing sizing and how each brand we stock actually fits.
Standard UK Clothing Size Chart
All the brands we stock use the same S–XXL scale, based on chest and waist measurement:
| Size | Chest (in) | Chest (cm) | Waist (in) | Waist (cm) |
|---|---|---|---|---|
| XS | 33–35 | 84–89 | 27–29 | 69–74 |
| S | 36–38 | 91–97 | 30–32 | 76–81 |
| M | 39–41 | 99–104 | 33–35 | 84–89 |
| L | 42–44 | 106–112 | 36–38 | 91–97 |
| XL | 45–47 | 114–120 | 39–41 | 99–104 |
| XXL | 48–50 | 122–127 | 42–44 | 106–112 |
Use this as your starting point, then check the brand notes below — the same letter size doesn't always fit the same way across brands.
How to Measure Yourself
Chest — wrap a soft tape measure around the fullest part of your chest, keeping it level under your arms.
Waist — measure around your natural waistline, just above the belly button.
Compare both measurements to the chart above. If you fall between two sizes, size up for a more relaxed fit.
Brand Fit Notes
Nike
True to size across the range, with a standard athletic cut. No need to size up or down for tees, shorts or tracksuits.
Asics
Also true to size. Asics activewear is consistent and reliable across tees, shorts and sets — order your usual size with confidence.
Berghaus
Fit can vary more here than with Nike or Asics, since Berghaus builds for outdoor performance rather than a single standard cut. Pieces are generally designed around three fit types — close-fitting for active movement, a balanced everyday fit, or a roomier cut with space to layer underneath. Check the product description for which applies, and message us if you're not sure — we're happy to check for you before you order.
Still Not Sure?
If you already own something from one of these brands, that's your best size reference. If it's your first piece from a brand, true to size is the right call in almost every case above.
Message us on Instagram @activefashion._ or via our contact page before you order and we'll help you get the right fit. You're also covered by our returns policy if it's not quite right.