What is input lag?
Input lag is the total delay between a user input (mouse click, keyboard press, controller button) and the corresponding visual change appearing on screen. It is measured in milliseconds.
A 5ms input lag monitor displays the result of your action 5ms after you performed it. A 100ms monitor delays it by 100ms. The difference is invisible in casual use but profoundly felt in fast gaming.
Input lag vs response time, the most common confusion
These two terms describe completely different things:
Response time (GtG, MPRT): how fast a pixel changes from one color to another. Affects ghosting and motion blur. A 1ms GtG monitor has fast pixel transitions.
Input lag: how fast the monitor processes and displays the incoming signal after receiving it. Affected by internal image processing, scaler, and display electronics.
A monitor can have 1ms GtG but 20ms input lag if it applies heavy post-processing. Conversely, a monitor with 5ms GtG but 1ms input lag will feel more responsive despite slower pixel transitions.
What causes input lag
How to measure input lag
Browser test (relative)
Our Input Lag Test measures click-to-flash latency including human reaction time. It gives you a relative baseline to compare after changing settings. Not absolute hardware input lag.
Hardware accurate
How to reduce monitor input lag
| Setting | Impact |
|---|---|
| Enable Game Mode / Low Input Lag | Removes image processing: -5 to -50ms |
| Use native resolution | Removes scaling latency: -2 to -10ms |
| Set to 144Hz+ | Each frame is shorter: -2 to -5ms |
| Disable HDR (Windows) | Removes HDR pipeline: -5 to -20ms |
| Use DisplayPort instead of HDMI | Minor, ~1-2ms less signal processing |
| Turn off V-Sync, use VRR | Removes V-Sync buffer: -15 to -30ms |
Typical input lag values (Game Mode on)
Does input lag actually matter?
For competitive gaming: yes. Studies show players can perceive and benefit from latency differences as small as 10ms. The tighter the feedback loop, the better your ability to make micro-corrections.
For casual gaming: largely no. A 15ms input lag monitor is imperceptible in single-player story games, strategy, or turn-based games.
For office and media: irrelevant. A 100ms TV works fine for watching movies.
The relationship with refresh rate
At 60Hz, each frame is present for 16.7ms. Even with 1ms input lag, the effective input-to-display latency is up to 16.7ms (the next frame slot). At 240Hz, frames are 4.17ms apart: a 1ms input lag monitor has true sub-5ms end-to-end latency.
Higher refresh rate is therefore the biggest input lag reducer, more impactful than any processing optimization.