What Is Delta E? Understanding the Color Accuracy Metric for Displays

Delta E (ΔE, written as 'Delta E' or 'dE') is the standard metric for measuring perceived color difference. It quantifies how far apart two colors are in human perception — a Delta E of 1.0 is the smallest color difference the average human eye can perceive. Lower Delta E values mean more accurate colors; higher values mean more visible color errors.

When a display reviewer says "this monitor has ΔE 1.5 after calibration," they mean the display's colors deviate from the target values by an average of 1.5 Delta E units — a deviation so small it's invisible to most viewers. When they say "ΔE 8 out of the box," they mean the display's colors deviate by 8 Delta E units — a clearly visible color error that most viewers will notice.

Understanding Delta E helps you evaluate display reviews, compare color accuracy across monitors, and set realistic expectations for calibration. This guide explains what Delta E measures, how it's calculated, what values mean in practice, and how to use it when shopping for a color-accurate display.

Delta E is calculated using the CIELAB color space (also called L*a*b*), which was designed to be perceptually uniform — equal distances in the color space correspond to equal perceived color differences. The original Delta E formula (ΔE76) is a simple Euclidean distance in CIELAB space: ΔE = √((ΔL*)² + (Δa*)² + (Δb*)²), where L* is lightness, a* is red-green, and b* is yellow-blue.

The original ΔE76 formula has known inaccuracies — it overestimates differences in saturated colors and underestimates differences in subtle hues. The updated ΔE2000 formula corrects these issues with weighting functions that better match human perception. Most professional display reviews use ΔE2000, which provides the most accurate perceived color difference measurement.

For practical purposes, you don't need to understand the math — just know that ΔE2000 is the current standard, lower is better, and the tiers (under 1, 1–2, 2–5, 5–10) translate consistently to real-world visibility. When reading display reviews, check which Delta E formula is used (usually ΔE2000) and compare values only within the same formula. For more on color science, see our color accuracy test and the color gamut test.

The Delta E target you should aim for depends on your use case. For general use (web browsing, gaming, media consumption), ΔE under 5 is perfectly acceptable — color errors are visible to trained observers but not disruptive to normal use. Most well-calibrated consumer displays achieve this with visual calibration alone.

For content creation (web design, YouTube video, social media content), target ΔE under 3. At this level, color errors are barely visible and your content will look consistent across most viewers' displays. A hardware colorimeter is recommended for reliable ΔE under 3 results — visual calibration alone may not achieve this consistently.

For professional color work (commercial photo editing, print proofing, broadcast video), target ΔE under 2. This requires hardware colorimeter calibration and a display capable of professional accuracy (factory-calibrated pro display like ASUS ProArt, Dell UltraSharp, or Eizo ColorEdge). For reference-grade work (cinema grading, high-end print), target ΔE under 1 — this requires spectrophotometer calibration and a reference-grade monitor ($2000+). For more on calibration, see our calibration guide and the best calibration tools guide.