Monitor Brightness Test

Press Full Screen on the solid white pattern to judge your panel’s peak output, spot APL dimming, and check that the centre and corners match. Then set a comfortable brightness for your room.

New to this? Here’s the plain-English version.

What this test is

A solid white screen that shows how much light your monitor actually puts out, and how even that light is across the panel.

How it helps you

It helps you set a comfortable brightness for your room — easing eye strain — and check whether an “HDR 1000-nit” claim really holds up.

What we’re checking

Your panel’s real peak white output, whether it dims on full-white screens, and whether the centre is brighter than the corners.

Black level test - You should barely see the differences

Look for any light bleeding or gray tint in the black areas. True black should show no light emission.

Press F11 or Full Screen · ← → patterns · Esc to exit

What Monitor Brightness Is

Brightness is measured in nits (cd/m²) — the panel’s maximum light output. A typical office monitor peaks at 250–350 nits; HDR-marketed panels reach 400–600 nits sustained; OLED and mini-LED can hit 1,000–2,000 nits on small highlights. The right level depends entirely on your room:

100

Dim room comfort

250

Typical indoor working level

400

Bright room / SDR peak

1000

HDR highlights only

Approximate nit levels and where they fit.

How to Use the Test

1Go fullscreen. Press Full Screen, then display the solid white full-field pattern — the most demanding state for the backlight.
2Judge peak white. On 100% white, note whether the panel looks strong and clean or dims after a moment (APL limiting).
3Check uniformity. Compare the white level at the centre versus the corners. A big difference is a uniformity issue, not a brightness one.
4Set your working level. Drop to your normal brightness (not maximum) and confirm white still looks clean — not clipped or tinted.

Recommended Brightness by Use Case

Environment	Recommended brightness
Dark room (evening)	80–150 nits
Standard office, indirect light	200–300 nits
Bright office, near a window	300–400 nits
Sunlit / outdoor-facing workspace	400+ nits
HDR highlight peaks (HDR content only)	600–1000+ nits

APL Dimming — Why “1000 Nits” Isn’t Always 1000

Many OLED and mini-LED monitors use ABL/ASBL (Automatic Brightness Limiter). When a large share of the screen is bright — high Average Picture Level — the panel lowers peak brightness to limit power draw and heat.

So a monitor advertised at 1,000 nits may only sustain 300–400 nits on a full white screen, with the peak reserved for small highlights. When comparing panels, look for “sustained” or “full-field” brightness, not just “peak”. This test’s full-white pattern is exactly the worst case that triggers APL limiting.

If white looks uneven rather than dim, that is a uniformity issue instead — check the uniformity test. And to judge how bright whites look against true black, pair this with the contrast test.

Brightness FAQ

How bright should my monitor be?+

Match brightness to your ambient light. A simple guide: the white on your monitor should look about as bright as a sheet of white paper in the same lighting. Most people are comfortable at 150–250 nits indoors, higher near a window.

Can high brightness damage my eyes?+

Running at maximum brightness in a dim room is tiring and can cause eye strain, but it does not cause permanent eye damage. Sustained discomfort is a signal to lower brightness and improve your ambient lighting rather than a sign of harm.

Does brightness affect monitor lifespan?+

On OLED, yes — sustained high brightness accelerates organic pixel wear and raises burn-in risk, so keep OLED below roughly 80% for long sessions. On LCD with an LED backlight, high brightness causes minimal long-term degradation.

What is the difference between nits and lumens?+

Nits (cd/m²) measure surface brightness — the correct unit for displays. Lumens measure total light output and apply to projectors and bulbs, not monitor panels. If a monitor is rated in lumens, treat the spec with suspicion.

Why is my 1000-nit monitor only showing 400 on white?+

That is APL/ABL dimming working as designed. When a large area of the screen is bright, OLED and mini-LED panels reduce output to limit power and heat, so the 1,000-nit rating only applies to small highlights. Compare “sustained” or “full-field” brightness, not just “peak”, when shopping.

Is a brightness difference across the screen a defect?+

A slight drop toward the corners visible only on full-field white is normal uniformity variation. A large, obvious difference — or coloured tinting across a big area — is a uniformity problem worth checking with the uniformity test and potentially returning.

Should I use auto-brightness?+

Ambient-light auto-brightness is convenient and keeps the screen comfortable as room light changes, but it can interfere with colour-critical work by shifting your reference. For editing, set a fixed brightness matched to a controlled room; for general use, auto-brightness is fine.

Related Monitor Tests

Contrast Test

Black levels and contrast ratio

Uniformity Test

Even brightness across the panel

Backlight Bleed Test

Edge light leak on black

Checking a whole new panel?

Run the dead pixel test and browse the full monitor test suite.

Monitor Pixel Test All Monitor Tests