Why color accuracy matters and when you need to test

If you edit photos, design graphics, or do any work where the colors on your screen need to match what prints or displays elsewhere, your monitor's color accuracy directly affects your output. A monitor that shows reds too bright or blues too dull will make your finished work look wrong to everyone else, even though it looks right to you. Testing your monitor tells you whether what you see is what you're actually getting.

You don't need to test if you're only browsing the web or writing documents. You do need to test if you're color-grading video, retouching photographs, choosing paint colors for a room, or designing anything that will be printed or viewed on other screens. The test itself takes 10 to 30 minutes and costs nothing if you use free tools.

Key Takeaways

  • Free online color tests like Lagom.nl and Eizo.com show whether your monitor displays blacks, whites, and grays correctly without any special equipment.
  • Your monitor's brightness, contrast, and color temperature settings affect test results, so adjust them to your working conditions before testing.
  • A hardware colorimeter (a small device that measures light) gives accurate readings but costs $100 to $400 and requires calibration software.
  • Software-based calibration tools like DisplayCAL (free) or X-Rite i1Profiler (paid) can create a color profile for your monitor if you have a colorimeter.
  • Room lighting, monitor age, and heat affect color accuracy, so retest every few months if color work is critical to your job.

Free online color tests you can run right now

The fastest way to check your monitor is to visit a color test website in your browser. Lagom.nl (a Swedish site, still active) has a suite of tests that show whether your monitor handles blacks, whites, grays, and color gradients correctly. Open the site, go to the LCD test pages, and look at each image in a dimly lit room—the same lighting you work in. If you can see all the gray steps in the gradient test and the black squares don't look blue or purple, your monitor is reasonably accurate.

Eizo.com offers similar tests under their monitor test section. Their gradient test is particularly useful: if you see banding (visible steps instead of a smooth fade), your monitor may not have enough color depth, or your graphics card settings are limiting it. Displaymate.com has more advanced tests, including ones for color blindness simulation and flicker detection, though the free version shows fewer options than the paid version.

These tests tell you whether your monitor has obvious problems, but they don't measure how far off it is or create a correction. They're a good first step before investing in hardware testing.

Adjusting your monitor settings before testing

Your monitor's brightness and contrast controls change how it displays colors, so set them to match your working environment before you test. If you edit photos in a bright office, set brightness higher than if you work in a dark room at night. There's no single "correct" setting—correct means matching your actual workspace.

Most monitors have a menu button (usually on the bottom or side). Look for Brightness, Contrast, and Color Temperature settings. Set brightness so that the white areas of your screen match the brightness of the wall or desk around it—not brighter. Set contrast so that you can see detail in both very light and very dark areas of a test image. Color temperature is usually labeled as Warm, Neutral, or Cool; Neutral (often labeled 6500K) is standard for color work.

If your monitor has a factory reset option in the menu, use it before adjusting. This clears any previous settings that might be throwing off the test. Write down your starting settings so you can return to them if needed.

Using a colorimeter for precise measurement

A colorimeter is a small device that sits on your screen and measures the actual light coming out of it. It's the only way to get a numerical reading of how far your monitor is from the standard. Common colorimeters include the X-Rite i1Display Pro (around $400), the Datacolor SpyderX Elite (around $200), and the BenQ SW240 (a monitor with a built-in colorimeter, around $600).

To use a colorimeter, you install the included software, attach the device to your screen, and run a calibration. The software displays colors on your screen, the colorimeter measures them, and the software creates a color profile—a file that tells your operating system how to adjust colors to match the standard. The whole process takes 15 to 30 minutes. After calibration, your monitor will be accurate to within 1 or 2 Delta E units (a measure of color difference that the human eye can barely detect).

Colorimeters are worth the cost if color accuracy is part of your job. They're not necessary if you're testing a monitor once to see if it's usable.

Free software calibration if you have a colorimeter

DisplayCAL (formerly ArgyllCMS) is free, open-source software that works with most colorimeters. It's more flexible than the manufacturer's software but has a steeper learning curve. read it from displaycal.net, connect your colorimeter, and follow the wizard. It will create a color profile and install it on your system.

Your operating system will then use that profile to adjust colors. On Windows, profiles are stored in C:\Windows\System32\spool\drivers\color. On Mac, they go in ~/Library/ColorSync/Profiles. You don't need to do anything with these files—the system finds them automatically—but knowing where they are helps if you need to move them to another computer or troubleshoot.

If DisplayCAL feels too technical, the manufacturer's software that comes with your colorimeter is simpler and works just as well for most users.

Factors that change color accuracy over time

Monitor color accuracy drifts as the monitor ages. The backlight (the light source behind the screen) gets dimmer and shifts color temperature over months and years. Room lighting also matters: a monitor that looks accurate in daylight may look too blue at night under artificial light. Heat affects accuracy too—a monitor that's been on for an hour may display colors slightly differently than when it's cold.

If you do color work regularly, retest every three to six months. If you've calibrated with a colorimeter, you can recalibrate on the same schedule. For casual color work, testing once a year is usually enough. If your monitor is more than five years old and you need high accuracy, consider replacing it—the backlight is likely degraded beyond correction.

When to call in a professional

If you're color-grading video for broadcast or print, or if your work is being sold and color accuracy is a contractual requirement, hire a professional to calibrate your monitor and your entire color workflow. They'll test your monitor, your graphics card, your lighting, and your display settings as a system. This costs $200 to $500 but ensures your work will match the client's expectations.

For most other work—photography, web design, general graphics—testing yourself with free tools or a colorimeter is sufficient. The goal is knowing whether your monitor is accurate enough for the job, not achieving laboratory-grade precision.

Frequently Asked Questions

Can I test my monitor on a laptop or tablet screen?

Yes, the same free online tests work on any screen. Laptop and tablet screens are often less accurate than desktop monitors because they're designed for brightness and viewing angles rather than color precision. If you do color work on a laptop, a colorimeter test is especially useful to know what you're working with.

What does Delta E mean, and what number should I aim for?

Delta E is a measurement of color difference. A Delta E of 1 or less is imperceptible to the human eye; 2 to 4 is very good for color work; 5 to 10 is acceptable for general use. Most colorimeter software will show you the Delta E after calibration. If it's above 5, your monitor may have a hardware problem or may be too old to calibrate accurately.

Do I need to recalibrate if I move my monitor to a different room?

If the room lighting is significantly different (bright office versus dim bedroom), yes—retest or recalibrate. If the lighting is similar, you don't need to. The color profile itself doesn't change, but your perception of accuracy depends on the light around the monitor.

Will a color test tell me if my graphics card is the problem?

Not directly. If your graphics card is set to 8-bit color instead of 10-bit or higher, you'll see banding in gradients on the Lagom or Eizo tests. Check your graphics card settings (Nvidia Control Panel, AMD Radeon Settings, or Intel Graphics Control Panel) and make sure color depth is set to the highest option. If banding disappears after changing this, the problem was your graphics card, not your monitor.

Is it worth buying an expensive monitor if I'm just starting out with color work?

Not necessarily. A mid-range monitor ($300 to $600) that you calibrate with a colorimeter will be more accurate than an expensive monitor you don't calibrate. Start by testing what you have, then upgrade if testing shows it's genuinely inaccurate. Many people discover their existing monitor is fine once they've adjusted the settings and tested it properly.