What Is Monitor Response Time?

Monitor response time is how fast a pixel can physically change from one colour to another — measured in milliseconds, and completely different from refresh rate, which is how oftenthe screen draws a new image. Response time is what decides whether motion looks clean or smeary. And the honest truth about the “1ms” number stamped on nearly every gaming monitor box: it is mostly marketing. It is a best-case figure measured under favourable conditions, often for a different metric than the one that matters, and it rarely reflects how the panel performs across real colour transitions. Understanding what response time really measures is how you stop buying by the sticker and start buying by the motion.

Response time is one of the most misunderstood specs in all of display buying, precisely because the number on the box is chosen to look impressive rather than to inform. Two monitors can both claim “1ms” and look dramatically different in motion. To see through that, you need to know the two things “response time” can mean, why manufacturers pick the flattering one, and how the overdrive setting that chases a low number can quietly make your image worse.

Response time vs refresh rate — not the same thing

These get conflated constantly, so let us separate them cleanly. Refresh rate, measured in hertz (Hz), is how many times per second the monitor draws a new image — 60Hz, 144Hz, 240Hz. Response time, measured in milliseconds (ms), is how quickly each individual pixel can finish changing colour when told to. They work as a pair: a high refresh rate asks the pixels to change very frequently, and if the pixels are too slow to keep up, you get a high refresh number attached to a smeary picture.

Think of it this way — refresh rate is how often you are handed a new photo; response time is how quickly the ink on each photo actually dries. A 240Hz panel with slow pixels is like being handed a new photo every four milliseconds while the previous one is still smudging. This is why response time and refresh rate have to be judged together, the same point we make in our 144Hz vs 240Hz guide: raw hertz is only half of motion clarity, and a fast panel at a lower refresh can look cleaner than a slow panel at a higher one.

GtG vs MPRT: the two numbers hiding behind “response time”

Here is the crux of the marketing problem. “Response time” can refer to two genuinely different measurements, and manufacturers quote whichever is lower:

• GtG (grey-to-grey)measures how long a pixel takes to transition from one shade of grey to another. This is the number most relevant to ghosting and smearing, because real game content is mostly transitions between similar tones, not full black-to-white flips. GtG is the more honest motion-clarity metric — but it varies enormously depending on whichtwo shades you measure, so a single “1ms GtG” figure is usually the single fastest transition the panel can manage, not its average.
• MPRT (moving picture response time)measures how long a pixel stays visible to your eye — it is really a measure of persistenceand perceived motion blur, and it is often achieved using backlight strobing rather than genuinely faster pixels. A monitor can advertise “1ms MPRT” while its actual GtG pixel transitions are far slower, because MPRT is measuring a different thing entirely.

So when a box says “1ms,” the first question is 1ms of what?A “1ms MPRT” panel can smear noticeably despite the sticker, because that number came from strobing, not from fast pixels. This is exactly why you cannot buy motion clarity from the spec sheet, and why panel-type matters so much — the trade-off between contrast and speed is the heart of our IPS vs VA guide, where VA's deep blacks come at the cost of slow, smear-prone dark transitions.

Why “1ms” claims are mostly marketing

Even taking GtG at face value, a headline response-time number is a best case, not an average. Real pixel transitions vary hugely: light-to-light greys are usually fast, but dark transitions — the black-to-grey changes that dominate shadowy game scenes — are often several times slower on the very same panel. The advertised figure cherry-picks the fastest transition and prints it on the box. There is no industry rule forcing an honest average, so the number is a marketing choice, not a measured promise about the motion you will actually see.

This is why independent measurement matters so much for response time specifically. Reviewers like RTINGS and motion specialists like Blur Busters measure response time across a whole spread of transitions and report an average, along with overshoot behaviour — a far more useful picture than one flattering number. We do not run a lab, so for response-time data on a specific monitor we point you to their measured results rather than repeat a spec-sheet claim.

Overdrive: the trade-off that decides real clarity

The setting that determines how close a panel gets to its rated response time is overdrive(labelled Response Time, OD, Trace Free, AMA, and other names depending on brand). Overdrive briefly over-volts the pixels to force them through their colour change faster, directly reducing ghosting. It is the single most important response-time control you have — and it comes with a trade-off that is the whole game.

More overdrive is not better. Push it too hard and the pixels overshoot their target colour, producing inverse ghosting: a bright halo or light trail leading or following moving objects, which is often uglier than the dark smear you were trying to remove. So overdrive is a Goldilocks setting — too little leaves a dark trail, too much adds a bright one, and the correct level is usually the middle or “normal”option, not the maximum. The “1ms” figure, if it is achievable at all, typically requires an overdrive mode so aggressive that it introduces visible overshoot — which is another reason the headline number rarely matches the setting you would actually want to use. The full step-by-step tuning process, including how to spot the sweet spot by eye, is in our monitor ghosting guide.

One more twist: persistence blur is separate again

Even a panel with genuinely instant pixels — like OLED, whose transitions are effectively immediate and which sidesteps conventional ghosting altogether — can still show some motion blur, and it is worth knowing why, because it is a third thing distinct from both GtG and refresh rate. On a normal (“sample-and-hold”) display, each frame is held on screen until the next one arrives, and your eye tracks moving objects smoothly across that held frame, which your brain perceives as blur regardless of how fast the pixels changed. That is persistence blur, and the two cures for it are a higher refresh rate (each frame is held for less time) or backlight strobing (the MPRT trick, which flashes the backlight to shorten how long each frame is visible). So “fast pixels” solves ghosting, but perfectly clean motion also depends on persistence — another reason a single response-time number can never tell the whole motion-clarity story on its own.

What response time you actually need

You do not need to chase the lowest number; you need a panel whose real average response time keeps up with its refresh rate. A rough, honest framing:

• At 60–75Hz, almost any modern panel's pixels are fast enough that response time is rarely the limiting factor.
• At 144Hz, the panel has about 7ms between frames, so a well-tuned average response time comfortably under that keeps motion clean. Most decent gaming IPS panels manage this.
• At 240Hz and above, the frame window shrinks to around 4ms, so genuinely fast pixels matter — this is where slow panels start to smear regardless of the Hz on the box, and where fast IPS or OLED pulls ahead.

Notice the pattern: a fast average response time is what lets a high refresh rate actually deliver clean motion. A “240Hz 1ms” VA panel with slow real-world dark transitions can look worse in a shadowy scene than a “144Hz” fast IPS panel. Buy the measured motion, not the sticker. When you are ready to shop, our best 1440p gaming monitors are screened for real motion behaviour, not just the response-time number printed on the box.

The honest summary

Response time is how fast pixels change colour; refresh rate is how often the screen updates; you need both to be good for clean motion. The “1ms” on the box is a best-case, cherry-picked number — often MPRT from backlight strobing rather than true GtG pixel speed — so treat it as marketing, not a measurement. What actually decides your motion clarity is the panel's average response time across real transitions, tuned with a sensible overdrive setting that avoids overshoot. Judge a monitor by independently measured response-time data and by whether its pixels can keep up with its refresh rate, and you will never again be fooled by two “1ms” monitors that look nothing alike in motion.