Originally, Blink use fallback fonts if the font loading isn't finished in 3 seconds. But this timeout value wasn't defined in any spec. Blink changes this timeout adaptively to improve performance on slow connections. If font-display feature is enabled, this change happens only if 'auto' is specified to follow the font-display spec. Otherwise, it happens always. The definition of slow connection would be changed in the field trial.



Specification link

Specification being incubated in a Community Group

Status in Chromium


Browser Intervention (tracking bug)

Consensus & Standardization

After a feature ships in Chrome, the values listed here are not guaranteed to be up to date.

  • No signal
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Chrome 49, the feature is enabled as a User-Agent Intervention. 2G Cellular connection will trigger the intervention. Chrome 53, network quality estimator has been used to trigger the intervention on effectively slow networks. This estimator-based intervention was enabled by default in Chrome 59. Developer tools shows a warning message when the intervention is triggered for each font. Web site owners can opt-out from the intervention by setting CSS font-display to other than 'auto'.

Search tags

Font, Fonts, WebFont, WebFonts, Intervention, User Agent Intervention,

Last updated on 2022-05-02