Test Profiles

Test Profiles allow you to change the conditions that your site is tested under. Calibre can emulate popular devices (like iPhones, iPads and Samsung Galaxy phones), throttle network connectivity, set custom headers or cookies, block ads or the execution of JavaScript.

Test Profiles can be found for each site in Calibre by navigating to Site → Settings → Test Profiles.

Test Profile list and creation screen

Default Test Profiles

When you add Sites, Calibre creates three default Test Profiles automatically:

NameDevice EmulationConnection Speed
Chrome Desktop

An average desktop-class device.
No device emulation. 1280×1024 px viewport.Cable
Motorola Moto G Power, 3G connection

An average phone with average mobile connectivity.
Motorola Moto G Power. 415×884 px viewport.Regular 3G
iPhone 12, 4G LTE

A fast phone with fast mobile connectivity.
Apple iPhone 12.
414×896 px viewport.

Device Emulation

We leverage Google Chrome device emulation with a few additional mechanisms to ensure the measured experience is as close to a real device as possible. When Calibre emulates a device, it sets the following:

  • Device viewport
  • Device User-Agent
  • CPU speed

All to reflect the hardware conditions of the selected device.

Current Devices

We selected the devices below to reflect market trends in adoption and a diverse set of resolutions, processor capabilities and price ranges.

NameYear of ReleaseViewportSingle Core Score1
Samsung Galaxy A122020360×800 px149
Samsung Galaxy Tab A720201428×857 px308
Motorola Moto G Power2020415×884 px311
Oppo Reno 72022360×662 px388
iPhone SE2022320×568 px535
Samsung Galaxy A52s2021412×915 px713
iPad Pro (3rd gen)2021834×1075 px1143
iPhone 112019414×896 px1311
iPad (9th gen)2021810×1010 px1326
iPad mini (6th gen)2021744×1133 px1564
iPhone 122020390×664 px1573
iPad Air (5th gen)2022820×1061 px1706

1 A single-threaded processor benchmark test provided by GeekBench aims to estimate how quickly a processor can perform various calculations. The higher the score, the better.

Discontinued Devices

These devices are no longer sold (discontinued). You can still use them for testing, but they will be deprecated in the future. We recommend using devices from the Current Devices section.
NameYear of ReleaseViewportSingle Core Score1
Motorola Moto G42016360×640 px112
Galaxy S52014360×640 px153
Nexus 5X2015412×732 px170
Nexus 6P2015412×732 px207
iPhone 62014375×667 px306
iPhone 72016375×667 px721
iPhone 52012320×568 px754
iPad (4th gen)2012768×1024 px807
iPhone 82017375×667 px909
iPad Pro (1st gen)20161024×1366 px1116

1 A single-threaded processor benchmark test provided by GeekBench aims to estimate how quickly a processor can perform various calculations. The higher the score, the better.

Emulated Network Connection Speed

Calibre limits the bandwidth available to the browser by using pre-configured network speed options that best reflect average global connectivity.

Those pre-configured options are:

No bandwidth throttling
Regular 2G300ms256 KB/s51.2 KB/s
Good 2G150ms460.80 KB/s153.60 KB/s
Slow 3G400ms320 KB/s320 KB/s
Regular 3G300ms768 KB/s256 KB/s
Good 3G150ms1.57 MB/s768 KB/s
Emerging markets 3G400ms3.2 MB/s3.2 MB/s
Regular 4G170ms12.19 MB/s3.15 MB/s
4G LTE70ms24 MB/s24 MB/s
DSL30ms2.10 MB/s1.05 MB/s
WiFi10ms31.46 MB/s15.73 MB/s
Cable20ms40 MB/s40 MB/s


Setting custom cookies can be helpful in a variety of scenarios. The most common implementations include:

  • Authenticating Calibre to your web application.
  • Disabling advertising to ease troubleshooting of developer-specific regressions.
  • Testing against an A/B test or staff-shipped feature.


Custom headers are useful for setting Authorisation headers for basic authentication or for triggering certain conditions for your Pages.

Blocking ads

Advertising often has a significant impact on site speed. When creating a Test Profile, select “Block ads” to analyze the impact on speed and accessibility. Calibre’s ad blocking feature is powered by uBlock.

Blocking third party scripts

Calibre automatically detects third party providers during testing, based on a custom instance of Third Party Web dataset. When creating or editing a Test Profile, choose which providers you would like to the requests will be blocked when Snapshots run.

Each provider is listed with a Last Detected date. Some of the registered third parties can no longer be present on your Site but were included in the past. When blocking, make sure to include active third parties for reliable results.

A list of all detected third parties in Test Profile creation flow

We recommend experimenting with disabling:

  • Chat widgets and communication tools.
  • Scripts providing polyfills.
  • Analytics software.
  • Bug tracking scripts.

Blocking JavaScript

Turning off JavaScript is an excellent strategy in discovering potential functionality and accessibility issues when JavaScript execution fails or is not reliable.

When creating or editing a Test Profile, select “Block JavaScript Requests” to ignore all external JavaScript requests. When JavaScript is blocked, all requests except inline script (<script>my script</script>) included on the page will be halted.

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