OLED, LCD, and the three different numbers all printed as brightness
One panel makes its own light and one is lit from behind, which decides contrast, black level and power draw. The brightness figure quoted alongside is usually a peak nobody sees in normal use.
An OLED pixel makes its own light. An LCD pixel does not: it is a shutter in front of a backlight that is running whether the pixel is showing white or black. Almost every practical difference between the two follows from that one fact.
What the structural difference buys and costs
Black is where it shows. An OLED pixel displaying black is switched off, so it emits nothing, and the contrast ratio is limited by stray reflection rather than by the panel. An LCD's shutter leaks, so its black is a dark grey, and in a dim room the difference is obvious without measuring anything.
Power follows the same rule, in a way that is counterintuitive. An LCD's consumption barely depends on what it shows, because the backlight is constant. An OLED's depends heavily: a dark interface genuinely costs less energy than a white one, which is why dark mode saves battery on one panel type and almost nothing on the other.
The costs are on OLED's side too. The blue emitter ages faster than the red and green, so a static element left in place for months can leave a faint permanent mark. Makers counter it by shifting pixels slightly and by limiting sustained full-screen brightness, which is one reason the peak figure and the everyday figure diverge.
What a nit is, and which nit you are being quoted
A nit is one candela per square metre, a measure of how much light the screen sends toward your eye. More nits is a brighter screen, and the reason it matters is sunlight: outdoors, the screen competes with reflected daylight, and losing that contest makes a display unreadable regardless of its contrast ratio in a dark room.
Three figures are in circulation, and they are routinely printed as though they were one:
Typical brightness is what the panel sustains across its whole area under manual control. It is the lowest of the three and the most honest for everyday use.
High-brightness mode is a full-screen level the phone allows only when the ambient light sensor sees bright sun, usually for a limited stretch. This is the number that decides outdoor readability.
Peak brightness applies to a small window of the screen, often a few per cent of its area, for a highlight in HDR video. It is the largest number and the one most likely to be on the box. No phone displays a white page at it.
A claim that omits which of the three it describes is not a specification. When two phones are compared on brightness and only one figure per phone is given, the comparison is usually between different quantities.
Refresh rate, the other number on the same line
Refresh rate is how many times a second the panel redraws, in hertz, and it is independent of both panel type and brightness. What is worth checking is whether the rate is genuinely variable and how far down it can go, because a panel that drops to a few hertz on a static page saves meaningful power while one that only switches between two high rates does not.
The chip driving all of this is the other half of the story: what a phone's system-on-chip contains.
Sources
- International Commission on Illumination (CIE), definitions of luminance and the candela, read 17 September 2026
- VESA, DisplayHDR performance criteria for peak and sustained luminance, read 17 September 2026
- Apple, iPhone display specifications, typical and peak brightness figures, read 17 September 2026
Terms defined here
- Nit
- A unit of luminance, one candela per square metre: how much light a surface sends toward the viewer. It measures the screen's output, not the light falling on it, which is why a sunlit screen needs more nits rather than fewer.
- Emissive display
- A panel where each pixel generates its own light, as in OLED. Black costs no light and therefore no power, which is what gives the technology its contrast ratio.
- Peak brightness
- The luminance a panel reaches on a small fraction of its area for a short time, typically for a highlight in HDR content. It is not a level the whole screen can sustain.
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