Laptop display specifications, line by line

The display is the part of a laptop you look at for every second you use it, and it is described in a specification by four or five numbers that are each more slippery than they look. Here is what each one is measuring, and what it is not.

Brightness: typical, and where

Brightness is quoted in candelas per square metre, commonly called nits. The figure in a specification is a typical value for the panel, measured under the manufacturer's conditions, usually at the centre of the screen on a full white field.

Two things it does not tell you. First, uniformity: the corners of a laptop panel are routinely dimmer than the centre, and the specification quotes the centre. Second, sustained brightness on an emissive panel, where the full-field figure and the small-highlight figure are very different numbers and the marketing quotes the highlight one.

What to do with it: treat the quoted figure as a rank, not a promise. It is a reliable way to sort panels against each other and an unreliable way to predict whether a given screen is usable outdoors.

Colour: coverage is not volume

Colour is quoted against a standard — the common web and general-use standard, or one of the wider standards used in photography and video. The important distinction is between coverage of a standard and volume relative to it. Coverage says what share of the standard's colours the panel can reproduce. Volume can exceed one hundred per cent simply because the panel goes outside the standard in some directions, which does not mean it covers the standard's own colours.

A panel described as exceeding one hundred per cent of a wide standard, with no coverage figure for the ordinary standard, is being described in the flattering direction. If colour accuracy matters to you, the figure you want is coverage of the standard you actually work in, and the delta-E error figure if the manufacturer publishes one.

Refresh rate, and whether the machine can feed it

A high refresh rate is only worth what the rest of the machine can supply. On a laptop with integrated graphics, a very high refresh panel will spend most of its life running at a fraction of its capability. On a gaming machine it is directly useful — with the caveat in our piece on graphics power budgets, which decides how many frames the chip actually produces.

Also check whether the panel supports a variable refresh rate and whether the laptop's display path exposes it. On machines that route the internal panel through the integrated graphics, some variable-refresh features are unavailable even though the panel supports them.

The figure nobody prints: backlight modulation

Many laptop panels dim by switching the backlight on and off rapidly rather than by reducing its current. A minority of people get headaches or eye strain from this, particularly at low brightness where the off periods are longest. Manufacturers essentially never state it.

It is measurable, and independent panel databases and review sites publish the measurement for many models, usually as a frequency and a modulation depth. If you are sensitive to it, that measurement — for the exact panel variant in the exact model — is worth more than every other line on the display specification. Which leads to the next problem.

The same model can ship different panels

A laptop model is frequently produced with panels from more than one supplier, with different brightness, colour and modulation behaviour, under the same marketing description. Which one you get is not knowable from the listing. It is knowable from the machine once you have it: the panel reports its own manufacturer and model identifier, which any hardware information utility will display, and panel databases will then tell you its measured characteristics.

The procedure for finding out — and for deciding whether to exchange a machine because of it — is in the panel lottery.

Resolution, aspect ratio and the thing worth paying for

Resolution is the one display figure that means exactly what it says. Aspect ratio is the one that quietly changes how much you can see: a taller ratio shows more lines of a document or a code file at the same diagonal, and the diagonal measurement itself means a smaller screen area on a wider ratio. If you are comparing a traditional wide panel against a taller one at the same quoted size, the taller one is physically larger in area.

Touch, matte and glossy

Touch panels are almost always glossy, because the touch layer is a glass sandwich. If you work under overhead lighting or near a window, that is a bigger daily cost than most specification differences. A matte finish diffuses reflections at a small cost in perceived contrast and colour saturation. The specification states the finish; it is worth reading, because it is a preference you cannot change later.