How to Measure for Running Shoes (Length, Width, Arch)
Running shoes need length, width, AND arch type. The street-shoe size that fits all day is half a size too small for a 10K. Here's the full sizing process plus the wet-paper arch test.
The Three Numbers Running Shoes Need
Three measurements, one trinity
Step 1 — Length (with Half-Size Bump)
- Stand barefoot on paper, heel against a wall.
- Mark longest toe and measure heel-to-mark in mm.
- Add 12mm (instead of street-shoe 10mm) for running-specific toe room.
- If you run more than 5 km regularly, add a full half-size beyond your street-shoe size.
Step 2 — Width
Mark the widest two points across the ball of your foot. Measure in mm. Compare to brand chart:
| Width (mm) at men's 9 | Letter (men) | Letter (women) | Use case |
|---|---|---|---|
| 94mm | B | AA | Narrow — Asics, Saucony stock B |
| 100mm | D | B | Standard medium |
| 103mm | — | D | Wide women's / men's standard |
| 106mm | 2E | — | Wide men |
| 113mm | 4E | 2E | Extra wide |
For more on widths see EE shoe widths decoded.
Step 3 — Arch Type (Wet-Paper Test)
- Wet your foot — fully soaked sole.
- Step onto dry brown paper or cardboard for 2 seconds.
- Lift and observe the wet footprint.
| Footprint pattern | Arch type | Pronation | Recommended shoe |
|---|---|---|---|
| Full footprint (no curve inside) | Flat / fallen arch | Overpronator | Stability / Motion control |
| Mid curve visible | Neutral arch | Neutral pronator | Neutral cushioned |
| Only ball, heel, outer edge | High arch | Underpronator (supinator) | Cushioning / Soft midsole |
If unsure, visit a running specialty store for a gait analysis (often free with shoe purchase). Gait video is more accurate than the wet test for prescriptive shoe choice.
Foot Length to Running Shoe Size
| Foot + 12mm | US Men | US Women | UK | EU | JP |
|---|---|---|---|---|---|
| 240mm | 7 | 8.5 | 6 | 39.5 | 24 |
| 250mm | 8 | 9.5 | 7 | 41 | 25 |
| 260mm | 9 | 10.5 | 8 | 42 | 26 |
| 270mm | 10 | 11.5 | 9 | 43 | 27 |
| 280mm | 11 | 12.5 | 10 | 44.5 | 28 |
| 290mm | 12 | 13.5 | 11 | 45.5 | 29 |
| 300mm | 13 | — | 12 | 47 | 30 |
Brand-Specific Sizing Notes
Brooks
Hoka
Asics
Nike
New Balance
Saucony
Common Mistakes
Wearing street shoes for running
Street shoes lack the cushioning and toe room running needs. Half a mile is fine; long runs cause injury.
Sizing only for length
Width matters as much for runners. Wide foot in narrow shoe = pinched toes by mile 3 = blisters.
Ignoring arch type
The wrong shoe for your gait causes IT-band, knee, and shin issues over time. Don't pick a stability shoe if you're a high-arch supinator (or vice versa).
Buying online without trying on first
Brand sizing varies enough that the same labeled size feels different across brands. Try in-person if you can; if you must buy online, order from a retailer with free returns.
Wearing shoes too long
Cushioning compresses at 300-500 miles. Replace before injury — track miles in a running app.
FAQs
Should running shoes be bigger than street shoes?
Yes — by half a size. Feet swell during runs.
How do I know my arch type?
Wet-paper test: full print = flat (overpronator). Mid = neutral. Narrow = high (underpronator).
What does pronation mean?
How your foot rolls inward when you land. Neutral = ~15%. Overpronation = excessive. Underpronation = rolls outward.
Road vs trail shoes?
Road: lighter, smoother. Trail: aggressive lugs, rock plates. Same sizing.
Do running shoes have width options?
Yes — most major brands offer 2E (wide) and 4E (extra wide).
How often should I replace running shoes?
Every 300-500 miles.
Three Numbers, One Right Shoe
Length, width, arch — get those three right and you've narrowed the running shoe shelf from overwhelming to a real shortlist. Pair with our foot length and width guide, and the EE width decoder.
Selling running shoes on Shopify? Width and arch fit drive returns.
Tailor Size Guide adds length + width + arch matching to every running shoe listing.