Monitor Response Time: GtG vs MPRT, and What 1ms Requires

The 1ms printed on a monitor box is a completely different number depending on how it was measured. 1ms (GtG) is how long one pixel takes to shift from one shade of gray to another. 1ms (MPRT) is how long that image lingers in your eye. And a 240Hz monitor physically holds each frame on screen for 4.17ms. Unless the backlight is switched off and on again between frames, MPRT cannot fall below that.

That is also why both numbers appear on the same panel. Manufacturers can pick the figure measured under the friendlier condition, and the two metrics were never measuring the same phenomenon to begin with.

GtG measures the pixel, MPRT measures your eye

KTC's buying guide separates the two this way: GtG measures how quickly a pixel physically changes from one shade to another, while MPRT measures how long an image remains visible on the retina rather than how fast pixels change color. The first is panel speed; the second is the length of the smear your eye perceives.

The measurement window hides a catch. The industry standard reads only the 10-90% luminance band, which skips the start and end of the transition where ghosting is most visible. The same guide notes that this window is what makes misleading claims possible. In practice, the time a panel needs to fully settle on a color is longer than the printed figure.

GtG measures how fast the panel changes; MPRT measures how long it holds the frame. Both have to fall for the smear to shorten.

Why 240Hz means 4.17ms

A conventional monitor runs sample-and-hold: it keeps showing the current frame until the next one arrives. So the time a frame sits on screen is fixed by the inverse of the refresh rate — 1,000 divided by the refresh rate in Hz. KTC's write-up gives the same arithmetic, noting that 60Hz carries roughly 16.7ms of persistence and 144Hz roughly 6.9ms.

Apply the Blur Busters rule of thumb and the smear converts into pixels: every millisecond of persistence adds about one pixel of blur per 1,000 pixels per second of movement. A fast flick in an FPS moves the image roughly 1,000 to 2,000 pixels per second, which produces the following.

Two things follow. First, halving the smear takes a doubling of refresh rate. Going 144Hz to 240Hz takes 6.9 pixels down to 4.2; 240Hz to 360Hz takes 4.2 to 2.8. Second, however close GtG gets to zero, nothing goes below the values in this table. GtG adds to these numbers; it does not replace them.

What a 1ms MPRT rating actually requires

So where does the 1ms (MPRT) on a 240Hz monitor come from? It is the value with backlight strobing — or black frame insertion — switched on, briefly cutting the backlight between frames. The trick shortens persistence by shortening how long the image is genuinely visible.

It costs something. KTC lists the tradeoffs as a 30-50% brightness loss, incompatibility with variable refresh rate, and strobe crosstalk artifacts. That means a dimmer picture in a bright room and giving up VRR in games with unstable frame rates. The 1ms (MPRT) on the spec sheet is the strobed figure; switch the feature off and you are back at 4.17ms.

Overdrive works similarly. Pushing extra voltage to accelerate transitions improves the GtG number, but overshooting the target brightness leaves bright halos — inverse ghosting — behind moving objects, another side effect the same guide flags. Reading panel specs works the same way as in the split between color gamut coverage and volume or the minimum requirements behind each DisplayHDR tier. Without the measurement condition, the number alone says little.

ClearMR: a ratio instead of a time

VESA's ClearMR, introduced in 2022, attacks the problem differently. VESA explains that CMR is defined as the ratio of clear pixels to blurry pixels, derived by photographing a moving test pattern with a high-speed camera. The stated motivation was that time-based metrics like MPRT cannot reflect enhancement techniques such as excessive overshoot and undershoot — which is why certification testing is run with backlight strobing disabled.

Per TFTCentral's analysis, the tiers run from ClearMR 3000 to 9000 in steps of 1,000, ClearMR 7000 means 65 to 75 times more clear pixels than blurry ones, and the bottom 3000 tier targets 90-120Hz displays so 60Hz panels generally do not qualify. Certification is not limited to monitors — it also covers laptops, tablets and TVs.

It is not the final word either. The same analysis notes a 260Hz LCD and a 165Hz LCD both landing on ClearMR 7000, and a 138Hz OLED sharing a tier with a 165Hz IPS LCD, raising the question of how well refresh rate is captured.

Who this suits, and when to wait

Judged on published specifications, the choice splits like this.

• Competitive FPS: start with refresh rate — persistence sets half the smear. Moving from 144Hz to 240Hz cuts more, by the table's arithmetic, than a 1ms GtG label does.
• Bright rooms: discount the strobed rating — 1ms MPRT is bought with 30-50% of the brightness. In a well-lit room it is hard to keep on.
• Always-on VRR: MPRT matters less — strobing and variable refresh generally cannot run together.
• Video and office work: not a priority — without 1,000px/s motion, a few pixels of smear never surface.
• Do not shop on ClearMR tier alone — products with different refresh rates land on the same tier, so check both.

The pre-purchase check is short: whether the parenthetical next to the response time says GtG or MPRT, which feature had to be on for the MPRT figure, and what that feature does to VRR and brightness. If bandwidth matters too, pair this with the bandwidth required for 4K 240Hz.

Sources

• Demystifying MPRT vs GTG: A Buyer's Guide to Monitor Motion Clarity — KTC
• VESA Brings Clarity to Motion Blur in Digital Displays — VESA
• VESA ClearMR Certification — Our Analysis, Thoughts and Concerns — TFTCentral
• VESA ClearMR Certification Service — Granite River Labs