Controller latency is the delay between pressing a button and the game reacting. A browser can’t see the whole chain, but it can measure the polling rate, how often new input arrives (125 Hz means every 8 ms), and your reaction time, which is enough to compare a cable with Bluetooth.
How to run a controller latency test
- ConnectPlug in or pair the controller, then press any button.
- Polling ratePress Measure, then keep a stick moving in circles for three seconds.
- ReactionPress any button the moment the box turns green, five times.
- CompareRepeat over USB and Bluetooth to see which is steadier.
What this test measures
Polling rate, or update rate, comes from the timestamp the Gamepad API attaches to every reading, which the W3C specification describes as “the last time the axes or buttons attribute for this gamepad was updated.” The test counts how often that changes: how many times a second the browser receives new data from the controller. At 125 Hz a new reading arrives every 8 ms; at 250 Hz, every 4 ms. A low or uneven rate adds delay before a game can react.
Reaction time runs from the moment the box turns green to the moment your press arrives. It includes your display, the computer and you, so it’s best for comparing setups: the same person on a cable and on Bluetooth, or on two screens.
What a browser can’t measure is true end-to-end input lag, from the button press to the change on screen. That needs external equipment, such as a high-speed camera or a latency analyzer.
USB vs Bluetooth
A cable is the most consistent connection. Wireless adds a small delay and can stutter with interference, which shows up here as a lower or jumpier polling rate. Browsers may also cap how often they read controllers, so compare results within one browser rather than against a spec sheet.
Lowering input lag
Improve the connection
- Use a USB cable for the lowest and steadiest delay.
- On wireless, keep the receiver or Bluetooth adapter in line of sight. A short USB extension that moves it out from behind the PC helps.
- Keep other 2.4 GHz devices, such as wireless headsets and routers, away from the adapter.
Cut display and game delay
- Turn on Game Mode on your TV; it often removes more delay than any controller change.
- In games that offer it, enable low-latency options such as NVIDIA Reflex or AMD Anti-Lag.
FAQ
Can a website measure true controller input lag?
No. True input lag runs from the button press to the change on screen, and measuring it needs external equipment such as a high-speed camera or a latency analyzer. This test measures the parts a browser can see: how often new input arrives, and your reaction time.
What is a good controller polling rate?
Many controllers update 125 to 250 times a second, and some gaming controllers reach 1000. Above about 125 Hz the gain is a few milliseconds, so a steady rate matters more than a high one.
Why is my polling rate lower than the controller’s spec?
The browser reads the controller on its own schedule, and some systems cap it. The number here is what the browser receives, which can be lower than what games get through native APIs. Compare results on the same browser.
Does Bluetooth add input lag?
Usually a little, a few milliseconds compared with a cable, and more with interference. If the polling rate drops or varies on Bluetooth, try a USB cable and compare.
Is 250 ms a good reaction time?
Yes, that’s typical. Most people land between 200 and 300 ms on a visual cue, and part of that is the display and computer, not you. Use the result to compare setups rather than people.