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Methodology

Every test on DeviceTests measures in your browser from what the browser reports, and every fact around it comes from a named source with its check date.

Choosing sources

A figure enters the data only with a source a reader can open: the standard or the maker's own page where it is public, otherwise a reference that quotes it. The source's title, publisher and address are stored with the figure, and so is the day someone last compared the two.

No figure is extended to a device or a version the source does not list, and no gap is filled by estimate. A value without a source is shown as not published.

Measurements

Every number a test shows is worked out in your browser by code with its own unit tests, from what the browser itself reports: audio samples, frame times, controller axes, touch points. Where a number is an estimate, the test says so and says what it cannot tell.

What the readings mean

Sound levels are given in dBFS: decibels below the loudest value a digital signal can hold, so 0 is the top and normal readings are negative. They describe the signal the browser receives, not the loudness in the room, which is why the decibel meter calls its numbers relative until you calibrate it.

Frame rates and refresh rates are measured from the times at which the browser draws frames in this window. A browser or a power-saving mode can draw fewer frames than the screen can show, so a result says what this window got, not what the screen is rated for. Controller, touch and mouse readings are the values the browser passes to the page, which can differ from what a game or the maker's own app reads.

Browser support

Which browser can run which test comes from MDN's browser compatibility data, a public dataset kept by browser makers and MDN, read by a script and pinned to one version, plus known limits from the browser makers' own notes and bug trackers. Each test page shows its support table, and a cell that has not been checked on a real device says so.

Checks before publishing

Each data file is validated against its schema on every build: required fields, units, links between tables and the date of every check. A page goes live only when its own words exist and pass a comparison with its neighbours, so no two pages say the same thing in different order.

What the dates mean

The date on a page is the day its facts or its words last changed, the same date the sitemap reports. Rebuilding the site without changing a page leaves its date alone.

Corrections

Reports of errors go through the contact page. A confirmed correction changes the data, the page and its date together.

Sources in use

Every source the data cites, with the day it was last checked.