Audio offset calculator

Tap along to a click twice — once on each pair of headphones — and this tells you how far apart your two devices are, in milliseconds. It runs entirely in your browser. Nothing is uploaded, including to us.

How to get a number worth having

1. Turn the volume up enough to hear the click clearly. Quiet clicks are hard to place in time.
2. Tap on the click, not after it. Do not try to correct for the delay yourself.
3. Keep the same hand and the same posture for both runs, or you are measuring your arm.
4. Do both runs within a minute or two of each other.

What the spread tells you, and why it matters more than the median

Each result shows a median and a spread. The median is the typical lateness. The spread is how much that lateness wobbles from tap to tap.

This distinction is the whole reason Bluetooth is hard. A fixed delay is solvable: a game can store it and shift its timing to match. A wandering delay is not, because there is no single number to store. Bluetooth typically adds somewhere around 150–250 ms, and it does not hold that figure still. So if your Device B shows a wide spread, that part is not something any game can calibrate away — including ours.

If you want frame-accurate timing, wired wins. That is true of every rhythm game, and we would rather say so than sell you a promise we cannot keep.

What a game can actually do about this

Store a separate offset for every output device, and notice when the route changes. Most rhythm games either keep one global offset or offer no calibration at all, which is why switching from your phone speaker to your headphones makes a game feel broken.