What is Input Lag? The Ultimate Guide to Monitor, Mouse, and Keyboard Latency

GearLab Hardware Column・Last updated: September 21, 2026

When discussing competitive gaming latency, players often complain: "I shot first, why did I die?" or "Flicking the mouse feels floaty and sluggish." That gap between "my hand moved" and "the screen responded" is exactly what Input Lag means—the silent killer of your K/D ratio.

To understand input lag, you must realize: from the millisecond you click your mouse to the moment the bullet fires on your screen, a high-speed relay race occurs. Watch the simulation below to see where this "signal highway" tends to get stuck in traffic:

* The animation and total latency figures are illustrative, meant to compare concepts; real numbers vary with the game, hardware, and settings. The "latency budget" table below explains how these two numbers add up.

First, Clear Up the Confusion: Input Lag vs. Ping vs. FPS

Players often lump three different kinds of "slow" together, but their causes and fixes are completely different:

The three influence each other but can't substitute for one another: a high FPS doesn't guarantee low input lag (a clogged render queue is the classic counterexample), and a low ping can't fix latency caused by your peripherals or monitor. "I shot first but died first" can be caused by network latency, by input lag, or by both at once. This article focuses on input lag.

Does 15 Milliseconds Really Matter?

The average human visual reaction time is around 200–250ms, so a 15ms difference isn't something you "see"—it's something you "feel." When aiming, your brain and hand constantly correct your movement based on what's on screen; the later the image arrives, the later the correction happens. It's most noticeable when flicking, tracking targets, and counter-strafing. For single-player story games or turn-based titles, the impact is much smaller.

1. Stage One: Peripheral Latency

This is the first runner in the relay race—your mouse and keyboard. When you press a switch, it takes time to send the signal to the PC.

• Debounce Delay: Mechanical contacts produce tiny "bounce" signals the instant they close. To prevent a single press from registering as multiple clicks, traditional mechanical switches typically add a debounce delay of around 5ms in firmware. Optical switches (which sense with light and have no contact bounce) and magnetic switches (which sense travel via the Hall effect) can bring this delay close to zero, which is why pros are shifting to them. Magnetic switches also enable Rapid Trigger: the key registers a release as soon as it moves back up slightly, without waiting to return to a fixed reset point, making rapid taps and counter-strafes (e.g., A → D) crisper.
• Polling Rate: How often does your mouse report to the PC? The standard is 1000Hz (1ms), and the latest esports mice support 4000Hz or even 8000Hz (0.125ms). Keep in mind, though, that the average extra wait added by polling is about half the polling interval. Going from 125Hz to 1000Hz is a huge improvement, but going from 1000Hz to 8000Hz saves only about 0.4ms more, while demanding more CPU resources—a clear case of diminishing returns.
• Connection Type: Wired and 2.4GHz dongle connections can be extremely close in latency, and mainstream wireless esports mice are used by many pros. Bluetooth, to save power, typically has connection intervals ranging from a few ms to tens of ms and is prone to interference and jitter, so it isn't recommended for competitive games.

2. Stage Two: PC Latency

After receiving the input, the game engine (mostly CPU-bound) updates the game state and ballistics, then hands draw commands to the GPU to render the frame. How long this takes is closely tied to how long each frame takes.

• Render Queue: In the past, CPUs would prepare several frames ahead in a queue to keep visuals smooth. In esports, this means what you see reflects your input from "a few frames ago"; the more GPU-bound you are, the longer the queue grows, and it can add tens of milliseconds. Technologies like NVIDIA Reflex and AMD Anti-Lag 2 (game support required) synchronize the CPU and GPU to keep the queue nearly empty, achieving "just-in-time" rendering. If a game supports them, you should enable them in the game's settings.
• Frame Rate and Frame Time: Time per frame = 1000 ÷ FPS: 60 FPS is 16.7ms, 144 FPS is 6.9ms, and 240 FPS is just 4.2ms. Your input has to "catch" the next frame to be drawn, so the higher the FPS, the shorter the average wait. That's why running 400 FPS on a 144Hz monitor can still feel more responsive than capping at 144 FPS.
• V-Sync: To prevent screen tearing, V-Sync holds frames until the monitor refreshes, often with extra buffering, which usually adds noticeable latency. Turn it off in competitive games. If you dislike tearing, use G-SYNC / FreeSync (variable refresh rate) instead, and cap your FPS slightly below the monitor's refresh rate (e.g., 141 FPS on a 144Hz monitor) so you don't hit the ceiling.

3. Stage Three: Display Latency

The GPU sends the rendered frame via DP/HDMI to the monitor. The monitor's internal chip processes the image and directs the liquid crystals or OLEDs to emit light—only then is the job truly done.

• Refresh Rate: A 60Hz monitor draws a new frame every 16.7ms, 144Hz is 6.9ms, 240Hz is 4.2ms, and 360Hz is just 2.8ms. Higher refresh rates mean you see the newest frame earlier. Also, most monitors update from top to bottom, so the bottom of a frame appears later than the top; the higher the refresh rate, the smaller that gap.
• Input Lag vs. Response Time: The advertised "1ms GTG" refers to pixel transition speed (reducing motion blur), usually measured at a specific overdrive setting; "Monitor Input Lag" is the processing speed of the monitor's scaler chip. They are different numbers—a 1ms response time does not mean 1ms of input lag. Many TVs have beautiful pictures but, without Game Mode turned on, suffer from 30ms+ of fatal input lag due to internal image processing such as noise reduction, motion interpolation, and picture enhancement!
• Panel Type and Extra Features: OLED pixel response is extremely fast (commonly rated around 0.03ms GTG), but that only describes the pixel itself; overall input lag still depends on signal processing. In addition, backlight strobing features (such as BFI or ULMB) improve motion clarity but usually add extra latency, so think twice before enabling them for competitive play.

The table also shows diminishing returns: going from 60Hz to 144Hz cuts nearly 10ms per frame, but going from 240Hz to 360Hz saves only another 1.4ms.

Adding It Up: The Latency Budget

Latency is additive: every stage contributes some time. The table below breaks the three stages apart and shows where the "50ms+" and "under 15ms" figures in the animation come from (the values are rough ranges compiled for easier understanding—measure your own setup for real numbers):

As the table shows, the biggest room for improvement is usually your slowest link, not your most expensive one.

Practical Optimization Checklist

Work through it in a "free first, spend later" order for the best value.

Free Settings (under 10 minutes)

1. Make sure your monitor is set to its highest refresh rate: Many people buy a high-refresh monitor while Windows is still stuck at 60Hz. Go to Settings → System → Display → Advanced display and pick the highest refresh rate your monitor supports.
2. Enable low-latency tech in-game: When supported, turn on NVIDIA Reflex or AMD Anti-Lag 2.
3. Turn off V-Sync: If tearing bothers you, use G-SYNC / FreeSync instead and cap FPS slightly below the refresh rate.
4. Disable the monitor's image processing: In the monitor's OSD menu, turn off dynamic contrast, noise reduction, motion interpolation, and image enhancement; on a TV, enable Game Mode.
5. Don't keep your GPU pinned at 100%: If GPU utilization stays near 100%, the render queue grows. In competitive games, it's worth lowering shadows, resolution scaling, or ray tracing in exchange for lower latency.
6. Close unnecessary background programs: Recording software, dozens of browser tabs, and RGB control apps can steal CPU resources and make frame times uneven.
7. Connect the monitor directly to the GPU: Use DP or HDMI straight to the graphics card, avoiding adapters, docks, or KVM switches, which may add extra latency.

Peripheral Upgrades

• For competitive games, move from Bluetooth to a wired or 2.4GHz dongle connection.
• 1000Hz polling is a fine starting point. If you want 2000–8000Hz, first make sure your CPU has headroom, plug the mouse directly into a rear USB port on the motherboard (no hub), and check that your in-game FPS doesn't drop.
• For keyboards, consider a magnetic-switch board with Rapid Trigger or a low-debounce optical-switch board, and lower the debounce time in the driver software as appropriate (test for accidental inputs).

Monitor Upgrades

• For competitive FPS games, prioritize 240Hz or higher with a fast panel (such as Fast IPS or OLED), and check third-party measured input lag rather than relying only on the "1ms" label.
• Your GPU and CPU must be able to reach matching frame rates, or a high-refresh monitor's advantage goes to waste.

How to Measure Your Own Input Lag

To find your actual numbers, try these methods, from simple to professional:

• In-game / driver stats: In games that support Reflex, NVIDIA's performance overlay can show "PC Latency." It covers only the PC side (not the peripheral or monitor), which makes it great for comparing before and after a settings change.
• DIY high-speed camera: Use your phone's 240fps slow-motion mode to capture the mouse button and the on-screen reaction (such as a muzzle flash) at the same time, then count the frames between the click and the image—each frame is about 4.2ms. The margin of error is one or two frames, but it's enough to reveal differences on the order of tens of milliseconds.
• Dedicated hardware: NVIDIA LDAT, the Reflex Analyzer built into some G-SYNC esports monitors, or community tools such as OSRTT use light sensors to detect changes in screen brightness and can measure the full "click-to-photon" latency.
• Check the basics first: Use GearLab's keyboard test tool to see whether keys are dropping inputs and whether reporting is stable, then use the Monitor Health Check to pick your monitor model, compare it with the official specs, and confirm it really runs at its maximum refresh rate and native resolution.

FAQ

How many milliseconds of input lag is considered good?

There's no absolute standard, but here are rules of thumb: for casual or single-player games, most people won't notice total latency under 50ms; competitive FPS players generally aim for under 30ms; and those chasing the extreme watch for under 20ms or even 15ms. Looking at the monitor alone (excluding pixel response), roughly 10ms or less is enough for most players, and beyond 20ms it starts to become noticeable.

My FPS is already high—why does it still feel laggy?

High FPS only shortens the "time per frame." If your GPU is near its limit and the render queue is long, or you're running V-Sync, a Bluetooth mouse, or a monitor with image processing left on, latency remains. Check Reflex, V-Sync, and your peripheral connection type first.

Are 2.4GHz wireless and Bluetooth mice OK for esports?

2.4GHz wireless mice from mainstream esports brands feel practically the same as wired ones and are widely used by pros. Bluetooth mice, with their longer and less stable polling intervals, aren't recommended for competitive games.

Is an 8000Hz polling rate worth buying?

For most people, 1000–2000Hz is plenty. Compared with 1000Hz, 8000Hz saves only a fraction of a millisecond, adds CPU load, and needs the mouse plugged directly into a motherboard USB port. Unless your CPU has headroom, you're pairing it with a 240Hz+ monitor, and you've already dealt with the other stages, your budget is better spent on a wired/2.4GHz connection, the monitor, and Reflex settings.

Can I use a TV for competitive gaming?

Yes, but you must enable Game Mode and choose a model that supports ALLM/VRR and has strong third-party latency measurements. Many mid-to-high-end TVs can get down to around 10ms in Game Mode at 120Hz; without Game Mode, it can be several times higher.