How to Check Your Monitor Hz (and Why Your Refresh Rate Might Be Wrong)
How to verify your monitor refresh rate with a browser Hz test. Common causes of 60Hz caps on 144Hz panels, frame time readings, and what the numbers mean.
An advertised maximum is not necessarily the active display mode. Check the operating-system refresh-rate setting and then use the refresh rate test as a quick cross-check.
Monitor refresh rate is how many times the panel redraws per second. If Windows still has you at 60Hz on a 144Hz panel, competitive games feel slightly off and you cannot pin down why.
When rated Hz and actual Hz disagree
| What you expect | What the test shows | Most likely cause |
|---|---|---|
| 144Hz | 60Hz | Windows display setting left at 60Hz after install |
| 165Hz | 120Hz | HDMI 1.4 bandwidth cap at 1440p resolution |
| 240Hz | 144Hz | DisplayPort cable rated for DP 1.2, not 1.4 |
| 144Hz | ~59-60Hz | Laptop on battery with power saving enabled |
| 165Hz | 60Hz | GPU control panel override forcing 60Hz |
Check the OS setting first, then the exact monitor manual, GPU port, cable specification, and selected input. Maximum modes vary by the complete signal path; do not assume one HDMI or DisplayPort result applies to every monitor.
How to run the test
Step 1: Set your OS refresh rate. Windows: Settings > System > Display > Advanced display > pick the highest Hz. macOS: System Settings > Displays > highest refresh option.
Step 2: Close background tabs and plug in your laptop. Background tabs throttle to near-zero fps. Battery saver drops many panels from 144Hz to 60Hz.
Step 3: Open the refresh rate test fullscreen. Windowed mode can add compositor overhead that shows up as jitter.
Step 4: Let it sample for 3-5 seconds. The detected Hz stabilizes after a few seconds. Watch the UFO motion bars to compare 30, 60, 120, and 240fps side by side.
Step 5: Fix and retest. Change the setting or cable that caused the cap. The result should be broadly consistent with the active mode, allowing for browser timing and variable-refresh behavior.
Run this alongside the dead pixel test when a new monitor arrives.
What the numbers mean
Detected Hz. An estimate of the frame cadence the browser receives, calculated from requestAnimationFrame intervals. A reading near 60Hz when you expected a high-refresh mode is a reason to check the active OS setting, selected display, cable/port, power mode, and VRR behavior.
Frame time. Milliseconds between consecutive frames. At 60Hz, each frame lasts 16.67 ms. At 144Hz, 6.94 ms. Lower frame time means less delay before visual updates reach your eyes.
Jitter. Variation between individual frame intervals. Browser scheduling and VRR can create variation; large, repeatable spikes are worth investigating with the game and display configuration you actually use.
Why 144Hz feels different from 60Hz
At 60Hz, you wait up to 16.6 ms for the next frame. At 144Hz, that window shrinks to 6.9 ms. More visual snapshots of moving targets per second.
Higher refresh rates shorten the time between display updates: a 60Hz frame interval is about 16.67ms and a 144Hz interval about 6.94ms. The perceptual and competitive value depends on the rest of the system, the game, and the player; there is no universal “best” refresh rate.
That 9.7 ms per frame adds up across a gunfight. You see the peek slightly sooner. Your crosshair correction starts from a fresher image.
When your monitor will not hit its rated Hz
Resolution too high for the signal path. Cable, port, monitor, GPU, color format, and resolution all affect the available modes. Check the exact monitor manual and the operating system’s list rather than relying on a universal HDMI or DisplayPort rule.
GPU output mismatch. Some monitors have different max refresh rates per port. HDMI might top out at 120Hz while DisplayPort handles 165Hz on the same panel.
Variable refresh rate conflicts. G-Sync or FreeSync with a framerate cap can produce odd browser readings. Disable VRR temporarily if numbers look wrong.
Integrated graphics on multi-monitor setups. Laptops driving an external panel through the iGPU sometimes default to 60Hz externally even when the internal screen runs higher.
Fix the bottleneck. Retest.
Your full setup check
After the Hz test passes, run a dead pixel test on the same panel, then a mouse test if you are checking the whole setup.
Display cadence can influence when a visual event reaches your eyes, but a browser reaction-time score also depends on the display, browser, input device, system load, and human variability. Use the reaction time test only for controlled personal comparisons.
Bottom line
Run a refresh rate test on a new monitor before you trust the box specs. Check OS settings first and compare the result with the monitor manual. Microsoft’s current Windows refresh-rate guidance explains where the active mode is selected and why available rates depend on the display and resolution.