# Reaction Speed Test

> Free online reaction time test. Click when the screen turns green and measure your reflexes locally in your browser. No download required.

- **Category:** Gaming
- **URL:** https://www.teafun.cyou/tools/reaction/
- **Privacy:** Runs entirely in your browser — no uploads, no account, no tracking.
- **Also known as:** reaction timer, reflex test, reaction speed, click when green, stopwatch, reflex timer
- **Related tools:** [CPS Test](https://www.teafun.cyou/tools/cps/), [Typing Speed Test](https://www.teafun.cyou/tools/typing/), [Aim Trainer](https://www.teafun.cyou/tools/aim/)
- **Tags:** Gaming, Input, Mouse

## About

Test your reaction time with a five-round click challenge.

## How to Use the Reaction Speed Test

Click Start. Wait — the panel stays red for a random 1-5 seconds, then flips to green. Click as fast as you can when you see green. **Do not anticipate**: clicking during the red phase is a false start and the trial is discarded (the randomized delay defeats rhythm-based guessing). After 5 valid trials, the tool shows your mean RT, best single trial, and a percentile against the population distribution (median adult simple visual RT is ~250 ms; competitive gamers and athletes often hit 180-200 ms; under 150 ms is near the human floor — true RT below ~100 ms is physiologically impossible because neural transmission alone takes that long, so sub-100 ms results indicate anticipation, not reaction). Your display latency matters: a 60 Hz monitor adds up to 16.7 ms of frame delay, a 144 Hz monitor 6.9 ms, plus USB-polling and OS input lag of 5-20 ms — the tool measures total system-plus-human RT, so comparing across different hardware is apples-to-oranges. Use the same device for before/after comparisons.

## Why Reaction Time Matters

Reaction time peaks in your **mid-20s** and declines ~0.5-1 ms per year afterward — a 60-year-old's simple RT averages ~30-50 ms slower than a 25-year-old's (Deary et al., 2011, UK cohort of 7,000+). RT also degrades with: sleep deprivation (24 hours awake = RT impairment equivalent to 0.10% blood alcohol, above the US driving limit), fatigue, alcohol, low blood sugar, and dehydration; it improves with caffeine (~10-30 ms faster within 30-60 minutes), warm-up, and consistent sleep. For drivers, the standard perception-reaction-time assumption in traffic engineering is 1.5 seconds (AASHTO), but that includes recognition + decision, not just the 250 ms simple RT — the gap is the cognitive processing of an unexpected hazard. For competitive gaming, the 50 ms between a 200 ms and 250 ms reactor is meaningful in fighting games and CS-style peeks but is dwarfed by game-sense and prediction at high levels. Tracking your RT over time catches sleep-debt and overtraining before they cost you — a sudden 30 ms slowdown is usually a recovery flag, not a permanent decline.

_SEO title: Reaction Speed Test – Measure Your Reflexes | TeaFun_

## FAQ

### Can I actually train my reaction time, or is it mostly fixed?

Some of it is trainable and some isn't. A warm-up, good sleep, and practising this exact task will shave a little off your time and — just as importantly — make it more consistent, but everyone has a biological floor set by how fast nerves carry a signal, so the gains are modest, not dramatic. If you want a faster number, chase consistency and alertness rather than one heroic click.

### Why do my five trials vary so much from one to the next?

Some spread is unavoidable — attention drifts, you blink, or you brace differently each time — so a 30-40 ms swing between trials is normal. That is exactly why the tool averages several attempts and trims the fastest and slowest: a single click is noisy, but the mean across a few trials is a far steadier picture of where you actually sit.

### Are my reaction-time results saved or shared anywhere?

They are saved locally on your device, but never shared. Everything runs in your browser: your average and best click are stored in your browser's own storage so a personal dashboard can show your best and recent trend — they are never uploaded to a server or compared on a public leaderboard. Because the data lives only on this device, no one else can see it, and clearing your browser's site data wipes it whenever you want.