Four fullscreen patterns, four monitor controls, ten minutes. This fixes the settings your eyes can judge — black level, white level, gamma, gray balance — and tells you plainly where only a colorimeter will do.
Run it
4 steps · fullscreen · ← → to move · Esc to exit
Have the monitor's menu buttons within reach — you'll use brightness, contrast and color temperature.
Before you start
Give the monitor 20–30 minutes to warm up — panels shift as they reach temperature. Kill anything that re-tints the screen: night light, blue-light filters, HDR on SDR content, "vivid" picture modes. Calibrate in the lighting you actually work in, because black level and brightness are judgments relative to the room.
The four steps
Set the black level with the brightness control. The screen fills with black plus six near-black squares. Turn brightness down until the darkest square disappears into the background, then up until it barely returns. The background must stay black, not gray.
Set the white level with the contrast control. A white field with six near-white squares. Raise contrast as far as it will go while every square stays distinct; if the brightest squares merge into the background or white takes on a color tint, back off.
Check gamma against the striped patches. Four striped squares sit next to solid gray partners, one pair per gamma value. Step back or squint: the pair that blends together is your current gamma. 2.2 is the target for everyday desktop work — adjust the monitor’s gamma setting if it has one.
Neutralize the grays with the color controls. A gray field and a 32-step grayscale ramp. Both should look colorless end to end. A warm or cool cast means the color temperature is off — pick the 6500K or sRGB preset, or trim the RGB gain controls until gray is just gray.
Order matters: brightness moves the black point, contrast the white point, and the gamma and color readings only mean anything once those two are planted. If you change brightness later, make one more pass.
What by-eye calibration can and can't do
It can put the monitor's own controls where they belong, which is most of the visible improvement on a screen that's never been touched — factory settings routinely ship with contrast clipping near-whites and brightness drowning the blacks. It cannot measure color. Your visual system rebalances white within seconds (stare at a blue-tinted screen and it reads neutral by the second minute), so judging absolute color by eye is structurally unreliable. A colorimeter doesn't adapt — that's the entire argument for owning one, and no web tool, ours included, replaces it. The longer version with the perceptual traps is in How to calibrate a monitor by eye — and when you need a colorimeter.
After calibrating, the dead pixel test and the gradient test on the homepage are the natural next checks — banding and uniformity problems become much easier to see on a screen with its levels set right.
How do I calibrate my monitor without a colorimeter?
Run the four steps above — black level, white level, gamma, gray balance — using the monitor’s own controls. That gets brightness and contrast genuinely right and catches obvious color casts, which is most of what makes an uncalibrated screen look wrong. What it can’t do is measure: by-eye calibration is limited by the very screen you’re judging with, and by your room lighting.
Do I need a colorimeter?
For color-critical work — print, photography you sell, grading — yes, and nothing on a screen can substitute for one. A hardware probe measures what the panel emits and builds an ICC profile; your eyes adapt within seconds and can’t. For everyday use and gaming, the by-eye pass gets you close enough that the difference stops being visible. We’d rather tell you that than pretend a web page replaces a $150 instrument.
What brightness should my monitor be?
Match it to the room. The working convention for office lighting is around 120 cd/m², but the usable rule is simpler: a white page should read like paper under your lights, not like a lamp. If the screen is the brightest thing in the room, it’s too bright — that’s where eye strain and crushed-looking photos both come from.
What gamma should I use?
2.2 — it’s what sRGB content is mastered for and what Windows and macOS both assume. Set anything else only when a workflow demands it (broadcast work uses BT.1886, some Mac video workflows 2.4). If the gamma step shows your panel sitting at 1.8 or 2.4 with no way to adjust it, the monitor’s “custom” or “sRGB” picture mode usually gets closer than the vivid default.
How often should I recalibrate?
Panels drift slowly — backlights lose brightness and shift warm over years, not weeks. Re-run the four steps when the room lighting changes, after moving the monitor, or every few months out of hygiene. With a colorimeter the usual cadence for critical work is monthly; by eye, “when something looks off” is honestly the right trigger.
Why do my monitor’s colors look wrong after calibration?
Usually something downstream is re-tinting the image: night-light / blue-light filters, HDR mode on SDR content, a “vivid” picture preset, or a stale ICC profile from a previous owner or driver. Turn those off, pick the standard or sRGB mode, and run the steps again. If grays still won’t go neutral at any setting, the panel itself is the limit — worth knowing before you buy used.