Draft data: Fit verdict is not fully verified yet. Do not treat as final advice. See how we score fit.

Does the Brooks Glycerin 21 Run Big or Small?

True to Size True to size
Stick with your usual size. · confidence: medium

What size should you buy?

Interactive suggestion based on this model’s fit offset (+0 US). Always confirm with a retailer return policy.

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Width
Plush midsole — length usually TTS
Break-in
None

Summary

Glycerin usually matches Ghost-style TTS length with a plush ride. Prioritize correct width over length tricks. Soft foam can make the shoe feel roomier underfoot without changing labeled size needs.

US / UK / EU / cm chart

General reference chart (not brand-official). US_M is this model’s primary system. Interactive tool above adjusts for this model’s fit offset; the table is crawlable reference.

USUKEUcm
65.53924.0
6.5639.524.5
76.54025.0
7.5740.525.5
87.54126.0
8.584226.5
98.542.527.0
9.594327.5
109.54428.0
10.51044.528.5
1110.54529.0
11.51145.529.5
1211.54630.0
1312.547.531.0

Where to buy

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