Tap or press space the moment the box turns green. Five rounds, about twenty seconds, and the answer is your median — then take it again four weeks into whatever you are trying, and see whether anything actually moved.
Your reaction time
– Five rounds and this fills in.
- Best round
- –
- Spread
- –
- Rounds counted
- 0 of 5
Add your age to compare this with the published numbers.
| Age | Study average | Measured like this page |
|---|
Your saved runs (this browser only)
This is a screen test, not a clinical one, and it does not diagnose anything. This is not medical advice: if your reaction time or your thinking has changed in a way that worries you, that is a conversation with your doctor or pharmacist.
Your reaction time is how long your eye, brain and hand take between a green box appearing and your finger moving. This test takes five rounds, keeps the middle one as your score, and puts it next to the averages a 1,469-person study published for your age group. Take it once today, and again four weeks into whatever you are taking.
How to use it
Sit still, put the phone down, and use the same hand and the same device each time. Tap the box (or press space) to start, wait while it is red, and tap the moment it turns green. If you press early the round is replayed and nothing is recorded — you cannot accidentally bank a 40 ms “score” that way. After five counted rounds the box shows your median, and Save this run keeps it in this browser with the date and a note you can type, like “week 3, 200 mg caffeine”.
Two rounds do not tell you anything. Five is enough to steady the number, and taking the whole test twice in a sitting will usually land within 10–20 ms of itself. That wobble is why a single comparison against a stranger’s score is close to meaningless, and why the useful comparison is against your own earlier run.
What the published numbers say
The averages in the table come from Woods, Wyma, Yund, Herron and Reed (2015), who measured simple reaction time in 1,469 people aged 18 to 65 on a calibrated rig. Their overall mean was 231 ms (SD 27 ms), and it rose with age at 0.55 ms a year — from 217.9 ms in the 18–24 group to 239.1 ms in the 59–65 group. That is about 21 ms across 47 years of life, which is smaller than most people expect and smaller than the difference between a good day and a bad one.
The same paper is the reason this page shows a second column. Their rig had 17.8 ms of hardware lag — 11.0 ms of display delay and 6.8 ms of mouse delay — and they corrected their mean from 231 ms down to 213 ms for it. Your browser has that lag too, and this page cannot measure it, so instead of pretending to subtract it we add it back to the study’s numbers. The second column is what their averages would have read on a screen like yours.
How much the equipment matters shows up when you compare studies. The UK Health and Lifestyle Survey (Der and Deary, 2006), measured on a handheld button box, produced a mean of 300 ms for its male sample — 284 ms after a later re-analysis removed unreliable cases. That is 50 to 70 ms slower than the screen-based study, for the same thing, in the same kind of people. A reaction time is a fact about the whole setup, not just about you.
Three worked examples
- A 29-year-old medians 268 ms. The published average for 25–31 is 221.0 ms, which reads as 238.8 ms on a screen. So the result is about 29 ms slower than average — noticeable, but one run on a laptop trackpad with a browser in the way is not a verdict.
- A 54-year-old medians 244 ms. The 52–58 band is 236.4 ms, or 254.2 ms measured like this page, so that is about 10 ms faster than the published average. Age costs far less here than the device does.
- Two runs four weeks apart: 281 ms, then 265 ms. That is 16 ms faster — real enough to note, small enough that a better night’s sleep would explain it. This is why the save button asks what you were taking: one person, two runs, is a note, not a trial.
Common mistakes
- Guessing the green. Anything under 100 ms is a press that was already moving, so it is refused. If you keep guessing you will get a worse median, not a better one.
- Comparing devices. A wired mouse on a 240 Hz monitor beats a phone browser by more than a decade of ageing does. Compare yourself with yourself, on the same device.
- Taking one round as the answer. Single rounds swing 100 ms. The median of five is the number worth writing down.
- Reading it as a brain age. There is no such measurement here. This is one simple motor task, and a slow score has more to do with your screen, your sleep and your hand than with your brain.
Frequently asked questions
What is the average human reaction time?
In the calibrated study behind this page, 231 ms on average across ages 18 to 65 (213 ms once their own hardware delay was removed). Measured in a browser like this one, the equivalent averages run from roughly 236 ms in your twenties to 257 ms in your early sixties.
What is a good reaction time?
There is no official cut-off, and this page deliberately does not grade you. Being within about 10 ms of the published average for your age is unremarkable, and being faster or slower than that by 20–30 ms is inside the range a different device or a bad night’s sleep can produce.
Does reaction time get slower with age?
Yes, but slowly: 0.55 ms per year of age in the study above, and the paper’s authors concluded that most of that increase comes from slower motor output rather than slower detection — their stimulus detection time did not change with age at all.
Can a supplement improve my reaction time?
Caffeine is the only common one with a consistent effect on simple reaction speed in published trials, and the effect is modest. Nothing on this page tests or proves anything about a product, and no supplement here treats or prevents any condition. What this tool gives you is a repeatable measurement so that you are judging by a number rather than by how you feel about the bottle you paid for.
Why does my phone score differently from my laptop?
Because you are partly measuring the hardware. Screen refresh, touch sampling and the browser all add lag, which is the same reason the study corrected 231 ms to 213 ms. Pick one device and stay on it.
Is this a test for ADHD, dementia or concussion?
No. It is not a clinical instrument, it does not diagnose anything, and it cannot screen for a condition. If your reaction time or your thinking has changed in a way that worries you, or you have had a head injury, talk to a doctor rather than a web page.
Where does my score go?
Nowhere. The rounds are timed in your browser, the saved runs sit in this browser’s own storage, and the note you type stays with them. Nothing you type here is sent to us.
Read next
- Creatine for the brain: what the sleep-deprivation trials found — where a measurable change in cognitive speed has actually been reported.
- Is there caffeine in nootropics? — often the reason a stack “works” on the first day.
- The best nootropic for brain fog, tested one at a time.
- Do nootropics help with memory? — what the evidence supports, and what it does not.
- How to focus better without Adderall.
This is not medical advice, and this test does not diagnose anything. Talk to your doctor or pharmacist before starting or stopping a supplement — especially if you take blood thinners, antidepressants or blood-pressure medication.