Reaction Time
Calculate Reaction Time by entering start and end dates or times. Get precise durations in years, months, days, hours, and minutes.
Formula
Reaction Time = Response Time - Stimulus Appearance Time
Reaction time is measured in milliseconds from when the screen turns green (stimulus) to when you click (response). Average human visual reaction time is 200-250ms.
Worked Examples
Example 1: Calculate Average Reaction Time
Problem:You recorded reaction times of 245ms, 218ms, 267ms, 231ms, and 254ms. What's your average?
Solution:Sum all times: 245 + 218 + 267 + 231 + 254 = 1,215ms Divide by number of attempts: 1,215 ÷ 5 = 243ms This is a good average reaction time, slightly faster than the population mean of ~250ms.
Result:Average reaction time: 243ms
Example 2: Reaction Time Improvement
Problem:Your average was 280ms last month. Now it's 245ms. What's your improvement percentage?
Solution:Improvement = (Old - New) / Old × 100 = (280 - 245) / 280 × 100 = 35 / 280 × 100 = 12.5% This is significant improvement - typical for regular practice over a month.
Result:12.5% improvement
Example 3: Percentile Ranking
Problem:If average is 250ms with standard deviation of 30ms, where does 190ms rank?
Solution:Calculate z-score: z = (value - mean) / std dev z = (190 - 250) / 30 = -2.0 A z-score of -2.0 means: ~97.7th percentile You're faster than about 98% of people!
Result:Top 2.3% (97.7th percentile)
Frequently Asked Questions
What is a good reaction time?
Average human visual reaction time is 200-250ms. Under 200ms is excellent, under 150ms is exceptional (professional gamer level). Over 300ms is below average. Factors affecting reaction time include age, fatigue, alertness, practice, and the sense being tested (touch is faster than sight).
How is reaction time measured?
Reaction time is measured from when a stimulus appears (screen turning green) to when you respond (clicking). This test uses JavaScript's Date.now() for millisecond precision. The random delay (1-5 seconds) prevents anticipation, ensuring genuine reaction is measured.
Why does my reaction time vary?
Reaction time naturally varies by 20-50ms between attempts due to attention fluctuations, minor distractions, and neural variability. Fatigue, caffeine, stress, and time of day also affect performance. Taking multiple attempts and averaging gives a more accurate measure.
Can reaction time be improved?
Yes! Reaction time can improve with: 1) Regular practice (5-15% improvement possible), 2) Good sleep (fatigue slows reactions), 3) Moderate caffeine (temporary boost), 4) Physical exercise (improves overall neural function), 5) Video games (especially action games). Age-related slowing can be partially offset by practice.
What's the fastest possible human reaction time?
The absolute physiological limit is approximately 100-120ms for simple visual reaction. This accounts for: light hitting retina (~1ms), neural processing (~20ms), signal to brain (~20ms), motor cortex processing (~30ms), signal to muscles (~20ms), muscle contraction (~20ms). Consistently achieving under 150ms requires peak conditions.
How does age affect reaction time?
Reaction time typically: peaks in late teens/early 20s (~200ms), gradually slows after 30 (~1ms per year), more noticeable decline after 60. However, experience and practice can compensate. A trained 50-year-old may outperform an untrained 20-year-old in specific tasks.
Why is the 'too soon' feature important?
Without random delay, you could anticipate the color change rather than react to it. The 'too soon' penalty ensures you're actually reacting to the visual stimulus, not timing your click. This makes the measurement a true reaction time test.
How do professional esports players train reaction time?
Esports pros: 1) Practice reaction-specific drills daily, 2) Maintain consistent sleep schedules, 3) Optimize monitor refresh rates and input lag, 4) Use aim trainers like Aim Lab or Kovaak's, 5) Stay physically fit (improves neural function), 6) Manage caffeine intake strategically. Many pros achieve consistent 140-170ms reactions.
Does screen refresh rate affect measured reaction time?
Yes! A 60Hz monitor updates every 16.7ms, so you might see the color change up to 16ms late. A 144Hz monitor (6.9ms) reduces this delay. Input lag (monitor processing time) adds more delay. For accurate measurement, the delay is consistent, so your times are comparable to your other attempts.
What's the difference between reaction time and reflexes?
Reaction time involves conscious perception and decision (see green → decide to click → click). Reflexes are unconscious automatic responses (touch hot stove → withdraw hand without thinking). This test measures reaction time. Reflexes, like the knee-jerk reflex, are faster (~30-50ms) because they bypass the brain.