How to Run the Response Time Test
- Launch the test above and press F for fullscreen. A box moves horizontally at adjustable speed.
- Observe the trailing edge of the moving object. A clean, sharp edge indicates fast pixel response. A dark smear trailing behind indicates slow GtG.
- Open your monitor's OSD (Response Time or Overdrive setting) and test each level while the test runs.
- Choose the setting with the least smearing and no bright halo ahead of the moving object.
This test is most useful at medium-to-fast movement speeds. Slow speeds make pixel transitions less visible; very fast speeds make overdrive coronas more apparent.
GtG vs MPRT — The Two Response Time Specs
Monitor manufacturers advertise two different response time figures. Understanding which one matters is critical to evaluating a panel's actual motion performance.
GtG (Grey-to-Grey) measures how long a pixel takes to transition from one specific grey shade to another. This is the real-world relevant spec for gaming and motion — it directly correlates with the ghosting you'll see in this test. A fast GtG means clean edges on moving objects; a slow GtG means visible trailing.
MPRT (Moving Picture Response Time) measures how long a pixel is visible per frame — it's a measure of perceived blur from sample-and-hold rendering, not pixel transition speed. MPRT is only achievable at its rated value when motion blur reduction (strobe backlight) is active.
The marketing problem: MPRT is always a lower number than GtG, so manufacturers advertise it as their headline "1ms" spec. A monitor advertised as "1ms MPRT" can still have a GtG of 8ms or more, producing significant ghosting at those transitions. The ghosting test above measures what GtG actually produces in practice.
Response Time by Panel Type
| Panel | Typical GtG | Ghosting Risk |
|---|---|---|
| TN | 0.5–2ms | Very low |
| Fast IPS / Nano IPS | 1–4ms | Low |
| Standard IPS | 4–8ms | Low–moderate |
| VA (grey transitions) | 4–12ms | Moderate–high on dark transitions |
| OLED | <0.1ms | Effectively none |
VA panels carry the largest caveat: their dark-to-grey transitions are significantly slower than their grey-to-grey figure suggests. The rated GtG for a VA panel typically measures a mid-grey transition; the dark transition that causes the visible smear in dark game scenes can be 3–5× slower.
OLED panels have no liquid crystal and therefore no GtG delay — response time is effectively instantaneous. The only motion artifact on OLED is image retention from static content, not ghosting from slow pixels.
Overdrive: How to Dial It In
Overdrive (also called Response Time, TraceFree, or AMA depending on brand) pushes extra voltage to the pixel to accelerate the transition. Getting it right eliminates ghosting without introducing overshoot artifacts.
Signs the overdrive is too low:
- Dark smear or shadow trailing behind the moving object
- Trailing is most visible on dark or high-contrast backgrounds
Signs the overdrive is too high:
- Bright halo or white corona appears ahead of the moving object (inverse ghosting)
- The leading edge looks brighter than it should
Dialing in the optimal setting:
- Start at the medium overdrive level
- Run this test at a moderate speed
- If you see dark trailing: increase by one level and retest
- If you see a bright corona: decrease by one level
- Optimal: minimal trailing AND no visible corona
Most monitors perform best at Medium or High. Extreme/Maximum settings commonly introduce coronas that are more distracting than the ghosting they eliminate.
Frequently Asked Questions
What is monitor response time?
Response time is how long a pixel takes to transition from one color to another, measured in milliseconds. Faster response time means less ghosting — pixels finish switching before the next frame arrives, leaving no visible remnant of the previous color.
What's the difference between GtG and MPRT?
GtG (Grey-to-Grey) measures pixel transition speed — the spec directly responsible for ghosting in games and video. MPRT (Moving Picture Response Time) measures perceived blur from sample-and-hold rendering with strobe backlight active. GtG is the more useful real-world spec; MPRT is lower and used more prominently in marketing.
How do I reduce ghosting with overdrive settings?
Open your monitor's OSD menu and find the Response Time or Overdrive option. Start at Medium, run this test, and adjust up or down based on what you see: increase if dark trailing is visible, decrease if a bright corona appears ahead of the moving object. The goal is clean edges with no artifacts in either direction.
Does response time matter for non-gaming?
For general productivity, web browsing, and video streaming at normal speed: no, response time is essentially irrelevant. Ghosting is only perceptible during fast lateral movement, which is uncommon in non-gaming content. For gaming, video editing scrubbing, and cursor-heavy work at high speeds, response time noticeably affects visual clarity.
Is 1ms response time actually 1ms?
For most monitors advertising 1ms: not in practical GtG terms. 1ms MPRT is achievable with strobe backlight enabled, but the underlying GtG — what determines actual ghosting — is typically 3–8ms on standard IPS panels and 4–12ms on VA panels for dark transitions. TN panels and fast IPS gaming panels (LG Nano IPS, IPS Black) can achieve genuine 1–4ms GtG figures.