The NavigatorConcurrentHardware mixin adds to the Navigator interface features which allow Web content to determine how many logical processors the user has available, in order to let content and Web apps optimize their operations to best take advantage of the user's CPU.

Note: This feature is available in Web Workers.

The number of logical processor cores is a way to measure the number of threads which can effectively be run at once without them having to share CPUs. Modern computers have multiple physical cores in their CPU (two or four cores is typical), but each physical core is also usually able to run more than one thread at a time using advanced scheduling techniques. So a four-core CPU may return 8. The browser may, however, choose to reduce the number in order to represent more accurately the number of Workers that can run at once


NavigatorConcurrentHardware.hardwareConcurrency Read only
Returns the number of logical processors which may be available to the user agent. This value is always at least 1, and will be 1 if the actual number of logical processors can't be determined.


The NavigatorConcurrentHardware mixin has no methods.


Specification Status Comment
HTML Living Standard
The definition of 'NavigatorConcurrentHardware' in that specification.
Living Standard Initial definition.

Browser compatibility

Feature Chrome Edge Firefox (Gecko) Internet Explorer Opera Safari
Basic support 37 (Yes) 48 (48) ? 24 ?
Available on Workers (Yes) ? ? ? (Yes) ?
Feature Android Webview Chrome for Android Edge Firefox Mobile (Gecko) Firefox OS (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support 37 37 (Yes) 48.0 (48) ? ? 24 ?
Available on Workers (Yes) (Yes) ? ? ? ? (Yes) ?

See also

Document Tags and Contributors

 Contributors to this page: jpmedley, libbymc, Sheppy
 Last updated by: jpmedley,