What is Monitor Brightness?
Monitor brightness is measured in nits (cd/m²) — candelas per square metre. It describes the maximum light output of the display. A typical office monitor peaks at 250–350 nits. High-brightness panels marketed for HDR reach 400–600 nits in sustained output; OLED and mini-LED peak brightness can reach 1,000–2,000 nits in small highlight areas.
Brightness requirements depend on your environment. For a dim room, 150–200 nits is comfortable. For a bright office with a window nearby, 300–400 nits prevents the screen from looking washed out. Running a monitor at maximum brightness in a dim room causes eye strain and accelerates OLED pixel wear.
How to Use the Brightness Test
Step 1 — Launch the test and go fullscreen. Press Launch Test, then F for fullscreen.
Step 2 — Display the white full-field pattern. A solid white screen at 100% measures the panel's full-field peak brightness. This is the most demanding state for the backlight.
Step 3 — Check brightness uniformity. Compare the white level at the centre versus corners. A notable difference in brightness across the panel is a uniformity failure, not a brightness failure.
Step 4 — Test at your working brightness setting. Set brightness to your normal level (not maximum) and check that white looks clean, not clipped or tinted.
Brightness Guidelines by Use Case
| Use Case | Recommended Brightness |
|---|---|
| Dark room (evening) | 80–150 nits |
| Standard office, indirect light | 200–300 nits |
| Bright office, near window | 300–400 nits |
| Outdoor-facing or sunlit workspace | 400+ nits |
| HDR highlight peaks | 600–1000+ nits (HDR content only) |
APL Dimming and Why It Matters
Many modern monitors — particularly OLED and FALD mini-LED — use ABL (Automatic Brightness Limiter) or ASBL (Automatic Static Brightness Limiter). When a large percentage of the screen is bright (high Average Picture Level), these circuits reduce peak brightness to limit power draw and heat.
This means a monitor advertised at 1,000 nits may only sustain 300–400 nits on a full white screen, with the peak only achievable on small highlights. Check manufacturer specs for "sustained" or "full-field" brightness versus "peak" brightness when comparing panels.
Frequently Asked Questions
How bright should my monitor be? Match brightness to your ambient light. A general guideline: the white point of your monitor should roughly match the brightness of a white sheet of paper in your current lighting. Most people work at 150–250 nits in typical indoor conditions.
Can high brightness damage my eyes? Running a monitor at maximum brightness in a dim room is tiring and can cause eye strain. It does not cause permanent eye damage, but sustained discomfort is a signal to reduce brightness and ensure ambient lighting is appropriate.
Does brightness affect monitor lifespan? On OLED panels, yes — running at sustained high brightness accelerates organic pixel wear. On LCD monitors with LED backlights, high brightness causes minimal long-term degradation. Running OLED monitors above 80% sustained brightness for extended sessions increases burn-in risk.
What is nits vs lumens? Nits (cd/m²) measures surface brightness — relevant for displays. Lumens measures total light output — relevant for projectors and light bulbs. For monitors, nits is the correct unit; lumens is not used to rate display panels.