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Note: This feature is available in Web Workers.
The capabilities of a client device largely depend on the amount of available RAM. Traditionally, developers had to use heuristics and either benchmark a device or infer device capabilities based on other factors like the device manufacturer or User Agent strings.
There are two ways to determine the approximate amount of RAM a device has: use the Device Memory JavaScript API or accept Client Hints.
You may query the approximate amount of RAM a device has by retrieving Navigator.deviceMemory or WorkerNavigator.deviceMemory.
You may also use the Client Hints HTTP Header with the Device-Memory directive to retrieve the same approximate RAM capacity.
Returns the approximate amount of device memory in gigabytes.
WorkerNavigator.deviceMemory Read onlyReturns the approximate amount of device memory in gigabytes.
| Device Memory API |
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This page was last modified on Dec 15, 2025 by MDN contributors.
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