On Running Sizing & Fit Guide UK
Getting the right fit in On Running shoes matters. Whether you're buying your first pair of Clouds or upgrading to LightSpray technology, sizing questions are the number one thing customers ask us in-store. As authorised UK stockists handling On Running daily, this guide covers everything: true-to-size advice, UK size charts, wide foot guidance, LightSpray fit, and how On compares to other brands.
Do On Running Shoes Run True to Size?
Yes — On Running shoes generally run true to size. The majority of customers who buy their standard UK shoe size find the fit accurate across the range. This applies to road running models like the Cloud 6, lifestyle shoes like the Cloudtilt, and training shoes like the Cloud X 4.
On designs their shoes around a standard last (the foot-shaped mould used in construction), and they use consistent sizing across men's and women's ranges. If you wear a UK 9 in most running shoes, you should be a UK 9 in On.
Quick Sizing Summary
- Road running shoes (Cloud 6, Cloudmonster, Cloudsurfer) — true to size
- Lifestyle shoes (Cloudtilt, Cloudnova) — true to size
- Training shoes (Cloud X 4, Cloudpulse 2) — true to size
- Trail shoes (Cloudvista, Cloudsoma) — true to size but slightly narrow in the midfoot
- Waterproof models (Cloud 6 WP, Cloudhorizon WP) — true to size; membrane adds no bulk
- LightSpray shoes — true to size with a tighter, second-skin feel
The one exception to note is trail models. Shoes like the Cloudvista 2 and Cloudsoma have a slightly narrower midfoot to keep your foot locked during uneven terrain. If you have wider feet, consider trying these in-store before purchasing.
On Running UK Size Chart
On Running uses standard UK sizing that aligns with most major running brands. Below is the conversion chart for men's and women's shoes, based on On's official sizing and what we stock at OD's.
Men's On Running Size Chart
| UK | EU | US | Foot Length (cm) |
|---|---|---|---|
| 6 | 40 | 7 | 24.5 |
| 6.5 | 40.5 | 7.5 | 25.0 |
| 7 | 41 | 8 | 25.5 |
| 7.5 | 42 | 8.5 | 26.0 |
| 8 | 42.5 | 9 | 26.5 |
| 8.5 | 43 | 9.5 | 27.0 |
| 9 | 44 | 10 | 27.5 |
| 9.5 | 44.5 | 10.5 | 28.0 |
| 10 | 45 | 11 | 28.5 |
| 10.5 | 46 | 11.5 | 29.0 |
| 11 | 46.5 | 12 | 29.5 |
| 12 | 47.5 | 13 | 30.5 |
Women's On Running Size Chart
| UK | EU | US | Foot Length (cm) |
|---|---|---|---|
| 3.5 | 36 | 5.5 | 22.5 |
| 4 | 37 | 6 | 23.0 |
| 4.5 | 37.5 | 6.5 | 23.5 |
| 5 | 38 | 7 | 24.0 |
| 5.5 | 39 | 7.5 | 24.5 |
| 6 | 40 | 8 | 25.0 |
| 6.5 | 40.5 | 8.5 | 25.5 |
| 7 | 41 | 9 | 26.0 |
| 7.5 | 42 | 9.5 | 26.5 |
| 8 | 42.5 | 10 | 27.0 |
How to Measure Your Foot
Stand on a sheet of paper, mark the longest toe and back of the heel, then measure the distance in centimetres. Match this to the foot length column above. If you're between sizes, go up to the next half size for running shoes or stick with the lower size for lifestyle shoes.
Are On Running Shoes Available in Wide Fit?
No — On Running shoes are standard width only. Unlike brands such as Saucony (which offers Wide and Extra Wide options) or New Balance, On does not manufacture any wide or narrow fit variants across their entire range.
That said, not all On shoes feel the same width. Based on our fitting experience:
More Accommodating
Road and lifestyle models like the Cloud 6, Cloudmonster, and Cloudtilt have a roomier forefoot that accommodates most foot widths comfortably at true to size.
Slightly Narrower
Trail models like the Cloudvista 2 and Cloudsoma have a tighter midfoot for terrain grip. Training shoes like the Cloud X 4 also fit more snugly for lateral stability.
Wide Foot Advice
- On Running's standard width works for most feet, including slightly wide feet
- If you have particularly wide feet (EE or wider), we recommend trying in-store before purchasing
- Do NOT go up a full size to compensate for width — this creates heel slippage and reduces stability
- Going up a half size can help if you're on the border
- If you need a dedicated wide fit, consider Saucony, which offers Wide and Extra Wide in many models
How Does LightSpray Fit?
LightSpray is On's revolutionary upper technology — a robotic arm sprays a single 1.5km filament directly onto the midsole to create a seamless, glueless one-piece upper weighing as little as 30 grams. The fit is distinctly different from traditional mesh uppers.
LightSpray Fit Facts
- True to size — buy your normal UK size
- Second-skin feel — noticeably tighter than standard On uppers
- Less stretch than traditional mesh — the precision-sprayed filament has minimal give
- Standard width only — not suitable for wide feet
- No break-in needed — race-ready straight out of the box
- Moulds to your foot over time for a personalised fit
- Neutral gait only — designed for neutral runners
The "second-skin" description is accurate. LightSpray uppers feel more like a sock than a shoe upper. They wrap the foot precisely, which is why they weigh so little. However, this means runners with wider feet or high insteps may find the fit too tight. We strongly recommend trying LightSpray shoes in-store at OD's before purchasing.
LightSpray Care Note
Do NOT machine wash LightSpray shoes. Brush off dry dirt for daily care. Hand wash with warm water only. These uppers are engineered for breathability, not waterproofing — road running only, not for trails.
On Running Sizing Tips from Our Fitting Room
We fit On Running shoes every day at OD's. Here's what we've learned from thousands of fittings:
- Afternoon fitting is best. Feet swell during the day. Fitting in the afternoon gives you the most accurate size for running.
- Wear your running socks. Thick trail socks vs thin road socks can make a half-size difference. Bring what you'll actually wear.
- Check the thumb test. With the shoe on, you should have roughly a thumbnail's width of space between your longest toe and the end of the shoe.
- Walk and jog in-store. On's CloudTec cushioning compresses underfoot — you need to feel the shoe in motion, not just standing still.
- Heel lock matters. Your heel should sit firmly without slipping. If it lifts during walking, the shoe is too long — do not size up to fix width problems.
- No break-in needed. Every On shoe should feel comfortable immediately. If it pinches or presses on day one, it's the wrong size.
Shop On Running at OD's
On Running vs Other Brands Size Comparison
One of the most common questions we get is how On Running sizing compares to Nike, adidas, Saucony, and Salomon. Here's the honest answer based on fitting hundreds of pairs in-store.
| Brand | Compared to On | Width | Notes |
|---|---|---|---|
| Nike | Same size | Similar (standard) | Nike runs slightly narrow in some models; On is more consistent |
| adidas | Same size | Similar (standard) | adidas sizing is consistent; direct match to On |
| Saucony | Same size | Saucony has Wide/Extra Wide options | If On is too narrow, Saucony Wide may solve it |
| Salomon | Same size | Similar (standard) | Salomon trail shoes feel slightly snugger due to sensiFIT upper |
| New Balance | Same size | New Balance has Wide/Extra Wide | NB also offers width options On doesn't |
| ASICS | Same size | Similar (standard) | ASICS is very consistent; direct match |
The Bottom Line
On Running fits true to size and matches the UK sizing of Nike, adidas, Saucony, Salomon, New Balance, and ASICS. You should buy the same UK size you wear in any of these brands. The only difference is width — On is standard width only, while Saucony and New Balance offer wider options.
Frequently Asked Questions
Do On Running shoes run true to size UK?
Yes. On Running shoes run true to size across the entire UK range. Road, lifestyle, training, and waterproof models all fit true to your standard UK shoe size. Trail models like the Cloudvista 2 are true to size in length but have a slightly narrower midfoot for terrain grip.
Should I size up in On Running shoes?
No. Buy your standard UK size. On shoes are designed to fit correctly at true to size with no break-in period. Going up a full size creates heel slippage and reduces the stability the shoe is designed to provide. If you're between sizes, go up a half size for running or stick with the lower size for lifestyle wear.
Are On Running shoes good for wide feet?
On Running are standard width only with no wide or extra-wide options. Road and lifestyle models like the Cloud 6 and Cloudmonster accommodate most foot widths comfortably. If you have particularly wide feet (EE or wider), try in-store at OD's before purchasing. For dedicated wide fit running shoes, Saucony offers Wide and Extra Wide options in many models.
How do LightSpray On Running shoes fit?
LightSpray shoes fit true to size but with a distinctly tighter, second-skin feel compared to standard On uppers. The precision-sprayed filament has less stretch than traditional mesh. They require no break-in and mould to your foot shape over time. Standard width only and designed for neutral runners. Not recommended for wide feet.
Do On Running shoes need breaking in?
No. Every On Running shoe is designed to feel comfortable from the first wear. CloudTec cushioning pods activate immediately, and the Speedboard provides propulsion from step one. If a shoe pinches or creates pressure points on day one, it is the wrong size — not a shoe that needs breaking in.
Is OD's an authorised On Running stockist?
Yes. OD's Designer Clothing is an authorised UK stockist of On Running. Every pair purchased from us is 100% authentic with full manufacturer warranty, sourced directly from official distribution. Visit us at 44 Barrow Street, St Helens (Mon-Sat 9am-5pm) for expert fitting advice.