How RunSized works

The problem we solve

Running shoes vary wildly in sizing. A Nike Pegasus 42 fits completely differently from a Hoka Clifton 10, even if both say "size 10". Wide-foot runners often get black toenails because they ordered wrong. Nobody had built a proper sizing database — until now.

How the data works

Every data point follows the same format: "I wear [Reference Shoe] in size [X] (fits me [rating]), and I bought [Target Shoe] in size [Y] which fits [rating]."

Aggregate enough of these and you can answer: "If you wear NB 1080v14 in a 10, what size should you get in a Hoka Clifton 10?"

Confidence tiers

We never fake confidence. Every shoe pair shows exactly how much data exists:

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No data

Nobody has reported yet. Be the first!

🟡

Early reports (1–9)

Show individual records. Take with a grain of salt.

🟢

Growing data (10–29)

Aggregated view. Reasonably reliable.

✅

Community verified (30+)

Strong recommendation. High confidence.

Source weighting

Not all data is equal. User-submitted reports are weighted at 1.0. Reddit-extracted data gets 0.6. Review site data gets 0.5. This means 20 Reddit comments = about 12 weighted reports. The confidence tier uses weighted counts, not raw counts.

Help us build this

Every submission makes the tool better. If you've bought a running shoe recently, it takes 90 seconds to report how it fits. That data helps the next runner get it right.

Report your fit