Monitor Brightness Test
Set your screen brightness for the room you are in. Match the screen to a sheet of paper, see the target nits for dark, office and bright rooms, run a quick shadow check, and work through an eye-comfort checklist with a flicker test. Free, runs in your browser.
1. Match your room
Pick the room you are in right now. Your brightness target depends on the light around you, not on the screen alone.
This is where most people should sit. The 120 nit figure is the usual calibration target for a normally lit room, and 160 to 200 suits a brighter office.
On a typical 300 to 350 nit monitor that is often 30 to 60% on the brightness slider. Panels differ a lot, so trust the paper test over the number.
The paper-white test
- Turn off auto-brightness, HDR, dynamic contrast and any eco mode for now.
- Open the white field below in full screen.
- Hold a sheet of plain white printer paper next to the screen, lit by your normal room light (not by the screen).
- Change the brightness in the monitor menu (or the laptop keys) until the screen white looks like the paper: not glowing like a light box, not grey and dull.
- Pick below how it looked before you changed anything to get advice.
Next to the paper, the screen white looked:
Typical maximum brightness
| Budget office monitor | 200 to 250 nits |
| Mainstream IPS or gaming monitor | 300 to 400 nits |
| OLED monitor, full white SDR | 150 to 275 nits |
| Laptop | 250 to 500 nits |
| Phone, outdoor boost | 800 to 2000+ nits |
A browser cannot read your screen's real output, so these are spec-sheet ranges, not a measurement. Rated "peak" figures on HDR screens apply to small highlights, not a full white page.
2. Quick shadow check
After setting brightness, make sure you have not lost the darkest shades. On the black strip you should see the 9 and 14 bars, ideally 5 too, while the black background still looks black. The grey ramp should step up evenly from 0% to 100%.
Bars missing, or black looks grey? Use the step-by-step black level test.
Full screen: click, tap, swipe, arrow keys or Space to move between white field, reading page and shadow strip. The X button stays on screen. Esc exits. The page cannot change your backlight; only the monitor menu or laptop keys can.
3. Eye-comfort checklist
Tick what is already true for your setup.
0/6Spot PWM flicker with your phone
- Set the screen to the low brightness you use at night, then open the white field in full screen.
- Turn off LED room lights if you can, since they can flicker too.
- Point your phone camera at the screen. Dark bands rolling across the image, or a pulsing picture in slow-motion video (240 fps), point to PWM dimming.
- Raise brightness to 100% and repeat. If the bands vanish, the panel uses PWM at lower levels.
Brightness vs battery on laptops
The backlight is often the largest single power draw on a laptop doing light work. Dropping from full brightness to the 120 to 200 nit range can add an hour or more on many machines, depending on the panel and the workload. On OLED laptops, dark themes save power too, because black pixels are off. On LCDs a dark theme saves almost nothing; only the backlight level counts. Auto-brightness on battery is worth keeping once your manual level is right.
Understanding screen brightness
Brightness, contrast and backlight: the naming mess
On most PC monitors and laptops, the brightness control dims the backlight, so the whole picture gets lighter or darker and black stays as dark as the panel allows. On TVs, and some monitors, the control called brightness instead sets the black level, while a separate backlight, OLED light or panel brightness setting controls light output. Turning up TV brightness to fix a dim picture just turns black into grey. Contrast sets the white level; push it too high and highlights clip, which the white level test shows.
Nits and auto-brightness
A nit is one candela per square metre, the standard unit for screen luminance. A sheet of paper in a normal office reflects roughly 100 to 150 nits, which is why the paper test works and why 120 nits is a common calibration target. Auto-brightness uses an ambient light sensor to follow the room, which helps once your baseline is right. It can lag, pump up and down, or sit too bright, so set it manually first and then adjust the auto curve.
PWM flicker and flicker-free claims
Many screens dim by switching the backlight or OLED pixels on and off very fast, called pulse width modulation. At low brightness the off periods get longer, and some people get headaches or eye strain from it even when they cannot see it. A "flicker-free" sticker usually means DC dimming or a very high PWM frequency, but some panels only stay flicker-free above a certain brightness. Test at the level you actually use, and check reviews that measure the frequency.
When the screen looks washed out
A washed-out picture is rarely too much backlight. Common causes are a PC sending limited range to a screen expecting full range, HDR switched on for normal desktop use, a viewing angle on a TN or VA panel, or room light reflecting off the screen. Check black first with the black level test, then the ratio between black and white with the contrast test.
Related tools
- Black Level Test: find black crush and HDMI range problems.
- Contrast Test: check the range between dark and light tones.
- White Level Test: spot clipped highlights and set contrast.
- Display Test: a full set of screen checks in one place.
Frequently asked questions
What is a nit?
A nit is one candela per square metre (cd/m²), the usual unit for how much light a screen gives off. White paper in a normal office reflects roughly 100 to 150 nits. That is why a lit room often aims near 120 nits, a dark room near 80 to 120, and bright daylight at 250 nits and up.
Does this page measure nits?
No. A browser cannot read the light coming off your screen. The figures under Target white are room targets, not a reading of your panel. The typical maximum table is a set of spec-sheet ranges. The paper match, the shadow strip and the checklist are things you judge by eye.
How do I do the paper test?
Turn off auto-brightness, HDR, dynamic contrast and any eco mode. Open the full-screen white field. Hold a sheet of plain white printer paper next to the screen, lit by the room, not by the screen. Change brightness in the monitor menu, or with the laptop keys, until the screen white looks like the paper: not glowing, and not grey. Then pick how it looked before you changed anything. The page cannot change the backlight.
How do I leave the full-screen test?
Tap the X along the bottom. It stays visible, with a dark fill, a white icon and a white border, on the white field, the reading page and the shadow strip, including on a phone. Press Esc to leave from a keyboard. Leaving also exits full screen when the browser entered it. If full screen is blocked, the same overlay still covers the page and X closes it. A click, a tap, a swipe or the arrow keys move between the three patterns. Space, Enter, Page Up, Page Down and Backspace do that too, even when X is focused, so tap X or press Esc to leave.
Does this page flash the screen to test flicker?
No. There is no strobe, and nothing starts flashing on its own, so a reduced-motion setting has no flicker pattern to turn off. To look for PWM, set the low brightness you use at night, open the white field, and turn off LED room lights if you can. Point a phone camera at the screen. Dark bands rolling across the picture, or a pulse in a 240 fps slow-motion video, point to PWM. Repeat at 100% brightness. If the bands vanish only then, the panel uses PWM at lower levels. Esc and X only close the field. Nothing keeps flashing after you leave or the page closes.
Are the match buttons and the checklist a measurement?
No. Brighter, it glows, About the same, and Greyer or dimmer only choose advice text. The six checklist boxes are notes you tick yourself: paper match, room versus screen, glare, the 20-20-20 habit, flicker at your usual brightness, and a warmer colour in the evening. The count is how many you ticked. None of them read nits from the panel.