Online Refresh Rate Test: Check Your Monitor's Hz Instantly
Refresh Rate Test is a free refresh rate test that starts the moment the page loads — no click, no download, no account. It measures your monitor's real active refresh rate live, using your browser's own frame-timing data, and shows it as one giant Hz number alongside the average frame time in milliseconds. Flip on the frame-time graph to see individual frames plotted over time — the fastest way to catch a stutter that a plain average hides. Nothing is uploaded.
How the Refresh Rate Test Works
Every time your browser draws a new frame, it fires a requestAnimationFrame
callback. This tool timestamps every one of those callbacks with
performance.now(), measures the gap between consecutive frames, and keeps a
rolling window of the last 120 gaps. It then averages that window — dropping the highest and
lowest 5% as outliers, so a one-off garbage-collection pause doesn't skew the reading — and
converts the result to Hertz. If the number lands close to a standard rate like 60, 120, or
144Hz, it snaps to that exact value, since that's almost always what your monitor is actually
built to run at.
How to Read Your Results (Hz Readout + Frame Time in ms)
The large green number is your live refresh rate in Hz — how many times per second your monitor is redrawing the screen. Give it one to two seconds after the page loads to settle on a stable reading. The smaller average frame time stat underneath is the same measurement expressed in milliseconds per frame — the two are mathematically linked (1000 ÷ frame time in ms = Hz), so a steady 16.7ms reads as a steady 60Hz, and 6.9ms reads as 144Hz.
- Wait a couple of seconds for the Hz number to stabilize
- Compare it to the rate your monitor is supposed to support
- If it's lower than expected, check your OS display settings and cable — see the FAQ below
Spotting Stutters with the Frame-Time Graph
An average can hide a lot. A monitor that alternates between 8ms and 25ms frames can still average out to a normal-looking 60Hz-ish number, even though it feels visibly stuttery. Turn on the frame-time graph and watch the line: a smooth, flat trace means consistent pacing; sharp spikes mean individual frames are taking far longer than the rest, which is what you feel as a stutter or hitch. It's a quick way to sanity-check that a high refresh rate is actually landing evenly, not just averaging out on paper.
Why the Test Pauses if You Switch Tabs
Browsers deliberately throttle requestAnimationFrame in background tabs to save
battery and CPU — some drop it to once a second or less. If this tool kept measuring while
hidden, it would report a false, artificially low Hz that has nothing to do with your actual
display. Instead, it detects when the tab goes into the background, pauses measurement, and
shows a warning banner. Switch back and it picks up cleanly from a fresh reading.
Frequently Asked Questions
What Hz is my monitor?
Open this refresh rate test and read the big number — it's your monitor's active Hz, measured live from real frame timing, not from a setting buried in an OS menu. It starts the moment the page loads, so there's nothing to click first. If the number looks lower than what you paid for, check the FAQ below on a 144Hz monitor showing 60Hz.
How do I test my monitor's refresh rate online?
Just open the tool — it measures automatically using your browser's own frame-timing API, so there's no download, no account, and no button to press. Give it a couple of seconds to settle on a stable reading, then read the Hz number. It works the same way on any monitor connected to any modern browser.
Why is my 144Hz monitor showing only 60Hz?
This almost always means the browser window or the whole display is actually running at 60Hz, not that the test is wrong. Common causes: the OS display settings weren't changed after plugging in a 144Hz monitor (Windows and macOS both default new displays to 60Hz), the cable or port doesn't support the higher rate (some HDMI cables and ports cap out at 60Hz — DisplayPort or a higher-spec HDMI cable is usually the fix), or the GPU is outputting to the wrong display in a multi-monitor setup. Check your OS display settings first.
What is frame time and why does it matter?
Frame time is how many milliseconds it takes to draw one frame — the flip side of Hz (1000 divided by frame time in ms gives you Hz). A steady 16.7ms frame time is a smooth 60Hz; a number that jumps around — 10ms, then 40ms, then 12ms — is a stutter, even if the average still works out to a normal-looking Hz. That's why this tool shows both: the average Hz for the headline number, and the frame-time graph to catch the jumps the average hides.
How do I check my refresh rate on Windows 11?
Windows 11: Settings → System → Display → Advanced display → check the value under “Refresh rate.” That tells you what Windows is set to send, but not what's actually reaching your eyes — a loose cable, a lower-spec port, or a game capping its own frame rate can all mean the real number is lower. Run this refresh rate test with nothing else running to see the number your monitor is actually drawing.
How do I check my refresh rate on Mac?
On a Mac: System Settings → Displays → select your display → check the “Refresh Rate” dropdown (only shown on Macs and external displays that support more than one rate). As on Windows, that's the requested setting, not a live measurement — this tool reads the actual redraw timing from the browser instead, so it catches cases where the display silently falls back to a lower rate.
How many Hz can the human eye see?
There's no hard cutoff — the eye doesn't sample frames the way a monitor does, and perception of motion smoothness, flicker, and input responsiveness keeps improving well past 60Hz for most people, which is why 120Hz and 144Hz+ monitors feel visibly smoother in side-by-side comparisons and competitive gamers often notice the difference up to 240Hz. Studies on flicker and motion perception have found sensitivity into the several-hundred-Hz range under the right conditions, so “the eye caps out around 60” is a myth worth retiring.
Does refresh rate matter for gaming?
Yes — a higher refresh rate shows more frames per second, which makes fast motion look smoother and cuts input-to-screen latency, both of which matter in competitive and fast-paced games. It matters less for slower, story-driven or turn-based games, where a stable 60Hz is usually plenty. If you just upgraded to a high-refresh monitor for gaming, use this test to confirm it's actually running at its rated Hz before you assume the panel or the game is at fault.
