Refresh Rate Explained
Hz, frame rate, response time and input lag are four different things that people use interchangeably. Here is what each one is, and which tool shows it.
Refresh rate is how often the screen redraws; frame rate is how often your computer produces a new picture. A high refresh rate helps only when frames arrive to fill it. Blur comes from how long a pixel stays visible, tearing from frames arriving mid-refresh, and input lag from the whole chain — BenQ defines it as "the total time required to show an action on the screen", of which the monitor's response time is only one part.
Four numbers get muddled together whenever screens are discussed: refresh rate, frame rate, response time and input lag. They describe different parts of one chain, and confusing them is why people buy the wrong thing.
The chain, in order
- 1
Your computer draws a frame. How many it draws per second is the frame rate, and it depends on the game or application, the graphics card and the settings.
- 2
The frame travels down the cable to the monitor, which is where the connection's own ceiling can quietly cap things.
- 3
The monitor redraws. How often it can do that is the refresh rate, in hertz.
- 4
The pixels physically change. How quickly is the response time, in milliseconds.
- 5
You see it. The whole journey, from your finger to the picture, is input lag.
A fast screen fed slow frames shows slow frames. The chain moves at the speed of its slowest link.
Refresh rate and frame rate
Refresh rate belongs to the screen; frame rate belongs to the computer. A screen redraws on its own schedule whether or not a new frame has arrived, so if frames arrive less often than the screen redraws, some redraws simply show the previous frame again.
The Refresh Rate Test estimates the rate your browser is drawing at from frame timing. It is deliberately described as an estimate: power saving, background tabs, variable refresh and browser limits all move it, and it is not a reading from your hardware. What it is good for is a sanity check — if a screen you believe is fast reports something much lower, the cable, the setting or the system is worth a look before the panel is blamed.
Where blur comes from
Blur is not the same as a low refresh rate. BenQ’s two response-time figures explain why:
| Figure | What it measures |
|---|---|
| Gray-to-gray | "How long it takes a pixel to change from one grey value to another grey value" — close to a hardware-level figure, unaffected by post-processing or frame rate |
| Moving picture response time | "How long a pixel remains apparent or visible on the screen"; the longer it stays, the more blur or trail a moving image leaves. BenQ calls this figure "very subjective" and frame-rate dependent |
That second row is the one you see as smearing behind a moving object. The Motion Blur Test shows it directly: one object crossing a flat field at a chosen speed, which is a comparison by eye rather than a measurement.
Where tearing comes from
Tearing happens when a new frame arrives while the screen is part way through drawing the previous one, so the top of the picture comes from one frame and the bottom from another. On a still image you never see it; on a fast horizontal pan it shows as a line where the picture does not line up.
The Screen Tearing Test sweeps a single bar for exactly this, and its own page is honest about the catch: browsers usually synchronize their frames, so a clean result in a browser is not proof that a game will not tear.
Variable refresh rate is the answer the industry settled on: the screen waits for the frame instead of redrawing on a fixed schedule. It reduces tearing. It does not make frames arrive faster, and no number is offered here for what it does to latency.
Where lag comes from
This is the one most often blamed on the monitor alone. BenQ defines input lag as “the total time required to show an action on the screen”, and is explicit that “response time forms a part of overall input latency” rather than being the whole of it. Its list of contributors runs from the input device — wireless or wired — through the computer’s processing, the cable, the monitor’s internal circuitry and its response time, to any image processing the monitor is doing, such as HDR handling or edge sharpening.
That last item is worth knowing about: picture processing costs time. If a monitor has a game mode, part of what it does is switch processing off, which is why the same panel can feel different in two modes.
The Input Lag Test estimates the whole chain and says so plainly: the number it gives includes your own reaction time, which is usually the largest part of it. Use it to compare one setup with another on the same day, not as a figure for your monitor.
What to do with all this
- Buying? Match the refresh rate to the frames your computer can actually produce, and treat quoted response times as the maker’s own figure measured their own way.
- Something feels wrong? Check the rate you are getting first, then motion, then tearing, and only then start changing settings.
- Comparing two setups? Use the same tool, the same room and the same day, and compare them with each other rather than with numbers from a review.
The monitor buying guide covers the rest of the specification sheet, and says as plainly as this page does which parts of it a browser can check. It is not published yet, so it is named here rather than linked.
Questions
Will a higher refresh rate make my games smoother?
Only if your computer can produce more frames than your current screen shows. A fast panel fed a low frame rate displays that low frame rate. Check what you are actually getting with the Refresh Rate Test before assuming the screen is the limit.
Is refresh rate the same as response time?
No. Refresh rate is how often the screen redraws, in hertz. Response time is how quickly a pixel changes, in milliseconds. A screen can redraw often while its pixels change slowly, which is what produces smearing behind moving objects.
What exactly is input lag?
BenQ defines it as "the total time required to show an action on the screen" — the whole path from your key press to the picture changing — and says "response time forms a part of overall input latency". It names the input device, the computer's processing, the cable, the monitor's circuitry and its image processing as contributors.
Why does the Refresh Rate Test sometimes read lower than my screen's rating?
Because it reports what your browser is drawing, estimated from frame timing, not what the panel is capable of. Power saving, a background tab, variable refresh and browser limits all lower it, and that is stated on the tool itself.
Does variable refresh rate reduce input lag?
It addresses tearing by letting the screen redraw when a frame is ready rather than on a fixed schedule. It does not make frames arrive sooner, and this page makes no numeric claim about its effect on latency.
How this guide was made
The input-lag definition and the list of contributors are quoted from BenQ's own knowledge center pages, with the dates they were read. Everything said about what the tools report describes ScreenTail's own tools as they are built, including the limits each one states.
No millisecond figures for particular monitors, and no claim about how much latency any technology removes: those are per product and a browser cannot verify them. No frame-rate targets either — how many frames a game needs is a preference, not a specification.
- 01The definition of input lag as the total time to show an action on screen, that response time forms part of overall latency, and the list of contributors from input device to image processing: BenQ, Gaming Monitor Input Lag Versus Response Time — retrieved Sep 23, 2026.
- 02The definitions of gray-to-gray and moving picture response time, and that the latter is subjective and frame-rate dependent: BenQ, How is Monitor Response Time Measured? — retrieved Sep 23, 2026.