Why is reaction time slower on a phone than with a mouse?
Because a touchscreen has more steps between your finger and the page than a mouse button does, and each step takes time. The page code is identical on both. What differs is the hardware around it.
| Step | Mouse and monitor | Phone |
|---|---|---|
| Seeing the change | A 60 Hz screen redraws every 16.7 ms, so the green arrives about 8 ms late on average | Same idea. Many recent phones refresh at 120 Hz, which halves that wait |
| Registering the press | A microswitch closes and the mouse reports it within 1 to 8 ms, depending on its report rate | The glass scans for your finger on a cycle, a touch controller filters the signal, then the operating system passes it on |
| Finger travel | The finger rests on the button, so it moves less than a millimetre | The thumb hovers above the glass and has to cross the gap. You control that distance |
| Measured total | 71 to 87 ms for the whole chain on desktop platforms (Anwyl-Irvine et al. 2021) | 35 to 140 ms for screen plus touch sensor alone, across 26 phones (Nicosia et al. 2023) |
The two totals are not the same measurement, so do not subtract one from the other. The desktop figure covers the whole path from the code deciding to change colour to the code logging the click, software included. The phone figure covers only the hardware. Nicosia and colleagues built a robot that tapped the glass and watched the screen, and ran it on 26 phones priced from under 100 dollars to over 1,000. What the study shows is the spread: the fastest and the slowest phones were more than 100 ms apart on hardware alone. How much your own phone adds depends on the model, and you have no way of knowing where it falls in that range.
The finger travel row is the only one you can shorten. On a mouse the finger is already resting on the button. On a phone the thumb floats above the glass, and the time it takes to come down is added to your score. This is why the reaction time test page tells you to keep the thumb hovering just above the screen.
How big is the gap in practice?
Tens of milliseconds on average. Every large dataset that recorded the device shows the same pattern. The biggest is from TestMyBrain, where Passell and colleagues (2021) compared 59,587 visitors. After controlling for age, gender and education, people on mobile devices, and on Android phones in particular, were significantly slower on reaction time tests than people on laptops and desktops. The authors attributed the difference to device latency rather than to the people.
This site sees the same direction. Every run is tagged as touch or mouse, never as who you are, and in the few hundred reaction runs collected so far the touch medians sit a few dozen milliseconds behind the mouse medians. Treat that as a direction only. The sample is far too small for a percentage, so the site does not print one. The age guide covers the other side of this effect, where an older crowd on slower phones makes browser age charts look steeper than laboratory ones.
A gap of that size is about as large as the swing inside one person. Woods and colleagues (2015) found that an individual's trials vary by about 40 ms around their own average from round to round. So a single phone run and a single laptop run can differ by 60 ms without anything changing in you.
Which number should you trust?
Both, as long as you keep them separate. The laptop number is not closer to your nervous system than the phone number; it simply has less hardware in the way. Neither one is a laboratory figure, because a lab measures and subtracts its own hardware delay and a browser cannot. The scores guide shows the screen scale and the lab scale side by side.
Compare a phone with a phone, and preferably with the same phone. Your records here are stored in the browser you used, so the phone history and the laptop history never mix. If you want to know whether you are getting faster, watch the median on one device over several weeks. Whether your phone is a slow phone is a separate question, and it can only be answered by comparing that phone with other phones.
The leaderboard works the same way. Every entry carries a small phone or desktop mark, so when a 190 ms score sits above your 300, you can check whether it came from the same kind of input before comparing yourself with it.
What does this site do about touch?
Three things, and none of them is a correction.
It records the tap at the moment of contact. A browser reports one event when the finger lands and another when it lifts, and older mobile browsers held the second one back by about 300 ms in case a double tap was coming. This test uses the contact event and turns the double-tap wait off, so the time until your finger lifts is not counted.
It does not subtract a phone allowance. The measured range of 35 to 140 ms is too wide for one number to be fair to everyone. A flat subtraction would flatter the slow phones and penalise the fast ones. The raw number appears as measured, and this page is meant to help you read it.
It records only the input type. The anonymous run statistics store touch or mouse and nothing else about your hardware, and the leaderboard shows the same mark next to each name. The privacy page lists exactly what is kept.
How do you get a fair score on a phone?
Use the same phone every time, held the same way. The hardware delay is fixed for that phone, so it drops out of any comparison you make with yourself.
Keep the thumb low. Hover it a few millimetres above the screen and tap lightly. The time is taken at contact, so pressing harder does nothing, and the distance the thumb falls is the only part of the phone's delay you can shorten.
Keep the page in front. The test stops and shows a notice the moment the tab is hidden, because browsers slow their timers in background tabs. On a phone that also means not switching apps between rounds.
If your phone has a 120 Hz screen setting, turn it on. It cuts the display wait from about 8 ms to about 4 ms on average. That will not close the gap to a desktop, but it helps.
Frequently asked questions
Should I subtract something from my phone score?
No. The measured hardware delay across phones runs from 35 to 140 ms, and you do not know where your phone falls in that range. Any number you subtract would be a guess. Keep the raw score and compare it only with your own earlier scores on the same phone.
Is a laptop trackpad a mouse or a touchscreen?
This site counts it as a mouse, because the pointer is precise and the page never sees a finger on the glass. A trackpad click still has its own physical travel, and most laptop screens run at 60 Hz, so a trackpad tends to score slower than a wired gaming mouse on a fast monitor. It belongs in the mouse history, but allow for that when you compare it with a desktop score.