The Key Question
Both high input lag and slow response time speed can ruin your gaming experience. However, too high input lag can make competitive gaming unbearable.
Answer: While both input lag and response time are equally important for a fluid gaming experience, too high input lag can make competitive gaming unbearable.
Luckily, most new gaming displays offer both low input lag and quick response time, so you won't have to compromise.
Understanding the Difference
Many people mistake response time for input lag when looking at the display's specifications. To clarify:
Input Lag
Input lag is the delay between the screen and your commands, such as a press on the keyboard or mouse.
This includes:
- Signal processing time
- Panel refresh time
- Display processing overhead
Impact: High input lag makes games feel unresponsive and can put you at a competitive disadvantage.
Response Time
Response time is the time pixels take to change from one color to another.
This is:
- Physical pixel transition time (usually GtG - Gray to Gray)
- Measured in milliseconds (ms)
- Determines motion clarity
Impact: Slow response time causes motion blur and ghosting behind moving objects.
Response Time Explained
What Does Response Time Affect?
Response time primarily affects motion clarity. When pixels can't change color fast enough:
- Moving objects leave a "trail" (ghosting)
- Fast camera movements become blurry
- Text in motion becomes hard to read
- Competitive tracking becomes difficult
GtG vs MPRT Response Time
Gray-to-Gray (GtG):
- Most common measurement
- Time to transition between different gray shades
- Standard for manufacturer specifications
Moving Picture Response Time (MPRT):
- Measures perceived motion blur
- Often shorter than GtG
- Used in marketing as "1ms MPRT"
- Usually requires backlight strobing (MBR)
Important: A monitor advertised as "1ms MPRT" may have 4ms GtG. MPRT numbers are often lower and don't represent the same thing.
Testing Response Time
At Display Ninja, response time is tested using:
- Professional equipment (photodiodes, oscilloscopes)
- Real-world game scenarios
- Various transition patterns (not just best-case GtG)
- Multiple overdrive settings
Input Lag Explained
What Contributes to Input Lag?
Total input lag includes:
- Peripheral latency (mouse/keyboard processing)
- USB polling rate (how often device reports)
- Game engine processing
- GPU rendering time
- Display signal processing
- Panel response/refresh time
Display-specific input lag is what monitor manufacturers can control - typically 5-20ms on gaming monitors.
How We Test Input Lag
Professional input lag testing:
- Leo Bodnar Lag Tester (dedicated hardware)
- High-speed camera analysis
- Time from signal input to on-screen display
- Multiple measurements for accuracy
Acceptable Input Lag Levels
Competitive Gaming:
- Under 10ms: Excellent
- 10-20ms: Good
- Over 20ms: Noticeable delay
Casual Gaming:
- Under 20ms: Good
- 20-40ms: Acceptable
- Over 40ms: Noticeable sluggishness
Non-Gaming:
- Under 50ms generally fine for office work
- Higher tolerable for video/media consumption
Which Should You Prioritize?
For Competitive Gaming (FPS, Fighting Games, Racing)
Priority: Input Lag
Why? Because:
- Input lag directly affects your reaction timing
- You can adapt to some motion blur
- You cannot adapt to delayed actions
- A 20ms delay is 1 frame at 60Hz - that's huge in competitive play
Ideal Specs:
- Input lag: Under 10ms
- Response time: Under 5ms GtG
For Casual/Single-Player Gaming
Priority: Balanced
Both matter, but you have more flexibility:
- Input lag under 20ms is fine
- Response time under 8ms acceptable
- Image quality can take precedence
For Content Creation/Productivity
Priority: Neither Critical
Focus instead on:
- Color accuracy
- Resolution
- Screen real estate
- Ergonomics
Input lag and response time are secondary for non-gaming tasks.
Real-World Impact
Scenario 1: High Input Lag, Fast Response Time
- No motion blur (clear image)
- Actions feel delayed and disconnected
- Aim feels "floaty" in FPS games
- Result: Unresponsive gaming experience
Scenario 2: Low Input Lag, Slow Response Time
- Immediate response to inputs
- Motion blur behind fast objects
- Smearing in fast camera movements
- Result: Responsive but blurry
Scenario 3: Low Input Lag, Fast Response Time
- Immediate response
- Clear motion
- Result: Optimal gaming experience
Scenario 4: High Input Lag, Slow Response Time
- Delayed response
- Motion blur
- Result: Poor gaming experience
Modern Gaming Monitors
The good news: Most modern gaming monitors (2020+) offer both:
- Low input lag (under 10ms typically)
- Fast response time (1-4ms GtG)
You generally don't need to choose between them anymore unless shopping budget or specific use cases.
What to Look For
Minimum Specs for Gaming:
- Input lag: Under 20ms (preferably under 10ms)
- Response time: Under 5ms GtG advertised
- Refresh rate: 144Hz or higher
Competitive Gaming:
- Input lag: Under 10ms
- Response time: 1ms GtG
- Refresh rate: 240Hz or higher
Conclusion
While both are important, input lag should be your priority if you have to choose, especially for competitive gaming. High input lag makes games feel unresponsive regardless of how clear the motion is.
However, modern gaming monitors typically excel in both areas, so focus on:
- Input lag under 10-15ms
- Response time under 5ms GtG
- Refresh rate appropriate for your GPU
- Panel type that suits your content (IPS for color, TN for pure speed, etc.)
Remember: Specifications are marketing. Look for professional reviews with actual tested measurements rather than relying on advertised numbers.