How fast is a human, really?
Simple visual reaction time — see a change, press a button — averages about 273 milliseconds on a desktop computer. That number is not mostly muscle. Roughly half of it is the time light takes to become a signal your visual cortex recognises, and only the remainder is the nerve and muscle work of moving your finger.
What the numbers mean
| Average | Reading |
|---|---|
| Under 200 ms | Exceptional — or you anticipated the flip |
| 200–250 ms | Fast, typical of practised gamers |
| 250–300 ms | Normal adult range |
| 300–400 ms | Slow — tired, distracted, or a laggy screen |
| Over 400 ms | Something is interfering; retest when rested |
What changes your score
- Hardware. A 60 Hz screen adds up to 16 ms of delay on its own; a wireless mouse adds more.
- Touch versus mouse. Phones are consistently 20 to 50 ms slower for the same person.
- Sleep. One bad night is worth more milliseconds than months of practice.
- Age. Reaction time is fastest in the early twenties and slows gradually after.
- Anticipation. Guessing when green will appear produces impossibly low numbers, which is why the delay here is random.
Does this measure intelligence?
Barely. Processing speed is one component of cognitive ability, and reaction time correlates with it weakly — enough to be interesting in large samples, nowhere near enough to say anything about an individual. If you want an ability estimate, take the culture fair IQ test instead.
How to get your best honest score
Use a mouse on a desk, sit still, and rest your finger on the button before the round starts. Do not try to predict the flip — an early click voids the round on purpose. Five rounds are averaged because a single trial is dominated by noise.
Frequently asked questions
What is a good reaction time?
Around 270 to 280 ms is average on a computer. Under 220 ms is genuinely fast; under 180 ms usually means you anticipated rather than reacted.
Why is my reaction time slower on my phone?
Touchscreens add input latency and the display adds more. Expect 20 to 50 ms slower than the same person on a wired mouse.
Does reaction time measure intelligence?
Only weakly. It relates slightly to processing speed but is not an IQ test.
Can I improve my reaction time?
A little. Sleep, practice and a low-latency screen help, but most people can only move 20 to 30 ms.
Why do I get a "Too soon" message?
You clicked while the screen was still red. The delay is randomised so the flip cannot be timed in advance.
Is this reaction time test free?
Yes, completely free online, no account, retake it as often as you like.