Response time and overdrive
Every gaming monitor claims 1 ms. Almost none of them achieve it across the range of colour transitions that actually occur, and the mechanism used to get close, overdrive, introduces its own artefact. Here is how to read the claim and how to tune your own panel.
Why the headline number is not the number
Pixel transition speed depends heavily on which two shades are involved. Transitions between dark shades are the slowest on LCD panels, often by a factor of five or more, because the liquid crystal has less voltage difference to work with.
A manufacturer measuring "1 ms GtG" has typically found the single fastest transition pair, measured it with overdrive at maximum, and used a measurement threshold that ignores the slow tail of the transition. None of that is fraudulent; all of it is unrepresentative.
The figure that matters for you is the average or worst-case transition across the full range, and it is only available from independent testing, not from the box.
The response time your refresh rate requires
| Refresh rate | Frame period | What a slow panel does |
|---|---|---|
| 60 Hz | 16.7 ms | Almost any panel keeps up |
| 144 Hz | 6.9 ms | Average IPS is borderline on dark transitions |
| 240 Hz | 4.2 ms | Only fast IPS, TN or OLED genuinely resolve every frame |
| 360 Hz | 2.8 ms | Very demanding. OLED or top-tier TN territory. |
| 480 Hz | 2.1 ms | Realistically OLED only |
This is the arithmetic behind a claim you will see repeated: a 240 Hz OLED often looks better in motion than a 360 Hz IPS. It is not brand preference, it is that one of them can complete its transitions inside a frame and the other cannot.
Tuning overdrive yourself
Almost every monitor ships with overdrive set conservatively or aggressively rather than correctly, and the correct setting depends on the refresh rate you actually run. Tuning it takes five minutes.
- Set your monitor to the refresh rate you play at.
- Open a moving-object test pattern (a UFO test or any horizontally scrolling high-contrast object).
- Start with overdrive off or at its lowest setting. Note the trailing smear behind the object.
- Step up one setting at a time. The smear should shrink.
- Watch for a bright halo appearing behind the object. That is overshoot: the pixel has gone past its target and is coming back. This is worse than the smear you were trying to remove.
- Step back one setting from where overshoot appeared. That is your value.
Retune if you change refresh rate
Overdrive tuned for 240 Hz is too aggressive at 60 Hz, because the pixel has far longer to settle and will visibly overshoot. Monitors with variable overdrive adjust automatically; those without do not. If you switch between a high refresh competitive title and a 60 fps single-player game, you may need two settings.
How each panel technology behaves
| Type | Typical real-world GtG | Overdrive needed? | Failure mode |
|---|---|---|---|
| OLED / QD-OLED | Under 0.1 ms | None | None. Remaining blur is persistence only. |
| Fast TN | 1 to 3 ms | Mild | Overshoot if pushed. Poor colour and viewing angles. |
| Fast IPS | 3 to 6 ms | Moderate | Dark transitions lag. Overshoot on mid-tones. |
| Standard IPS | 5 to 12 ms | Heavy | Visible smear at 144 Hz and above. |
| VA | 4 to 25 ms | Heavy | Severe dark-transition smearing, the classic VA black smear. |
Related reading
- Panel technologies compared in full.
- Motion clarity and backlight strobing, the other half of moving-image quality.
- Refresh rate, which response time caps.
Frequently asked questions
What is grey-to-grey response time?
The time a pixel takes to change from one shade to another. It is measured across many pairs of shades and the results vary enormously: dark-to-dark transitions are typically far slower than mid-tone ones. The single number in marketing is usually the fastest transition measured with maximum overdrive, which is not representative of what you see.
What is overdrive?
The monitor briefly drives a pixel past its target voltage to make it change faster, then settles it back. It genuinely reduces transition times. Push it too hard and the pixel overshoots its target, producing a bright trail behind moving objects known as inverse ghosting or overshoot.
What overdrive setting should I use?
The highest one that does not produce visible inverse ghosting at your refresh rate. Use a moving-object test pattern, step through the settings, and look for a bright halo trailing the object. Step back one when you see it. Note that the correct setting changes with refresh rate, which is why variable overdrive is a genuinely useful feature.
How fast does a pixel need to be for my refresh rate?
Ideally the transition should complete within one frame period. At 144 Hz that is 6.9 ms, at 240 Hz it is 4.2 ms, at 360 Hz it is 2.8 ms. A panel with 8 ms real-world transitions is not delivering distinct frames at 240 Hz regardless of what the box says.
Is OLED response time really instant?
Effectively, yes. OLED pixels emit light directly and switch in well under 0.1 ms, so there is no transition smear and no need for overdrive at all. The remaining motion blur on an OLED is persistence blur from sample-and-hold, which is a property of how long each frame is displayed rather than of the pixels.