Whatever screen you’re reading this on is probably emitting several hundred candles’ worth of light per square meter. That’s right – candles are still the base unit of light measurement, and if you’re screen-shopping, you’ll probably come across the “nit” unit, which tells you how much candlelight per square meter your screen can emit. Nits can be important if you plan to use your device outdoors often (or if there’s a head lice outbreak, or if you’re very picky), but are just one element of a high-quality screen.
Candelas, Nits, and Lumens 101
Imagine you have a candle inside a cube with a total surface area measuring one meter by one meter (about the size of a bath towel or 20 iPads that have somehow been made into a cube). The total amount of light coming out of that candle at its source is about “one candela”.
All the light hitting the walls of the cube equals “one nit,” which is technically defined as “one candela per square meter.” Every additional candle you add to the cube will add another candela of luminosity, and, therefore, another nit, since the square meter now has more light in it. If you managed to get 400 candles/nits into the cube before it burst into flames, the light per square meter would be 400 nits, which makes for a pretty nice laptop screen.
Because this is a per-square-meter measure, screen size and nits aren’t related. Movie theater screens, which are exclusively used in dark environments, are usually around 50 nits, while smartphones, which get a lot of outdoor use, tend to be at least three or four hundred.
A theater projector is probably emitting more total light (measured in lumens) than any smartphone, but the phone packs more light into a smaller space. That’s why using a phone during a movie is so taboo: with at least ten times the candela per square meter than the screen, it’s basically a magnesium flare in a dark theater.
If you skipped down to the end of that hoping to find the super-simple summary, here it is:
- Candela = about the light from 1 candle
- Nit = the light from 1 candle per square meter
- More nits = more candles per square meter = brighter display
Nits: what are they good for?
If you’ve ever tried using a dim device on a sunny day, you’ll understand why nits matter. Your display needs to be brighter than the light sources around it to be clearly readable. On the other hand, if your device never leaves the basement, you probably aren’t turning up the brightness all the way anyway, so having more nits wouldn’t help much.
Unless that device happens to be an HDR (High Dynamic Range) TV, that is. The whole thing that makes these TVs better is that they can show brighter brights and true black. A Sony prototype HDR TV was able to hit 10,000 nits, though most HDRs max out around 2,000.
How many nits does a laptop/smartphone/TV need?
We don’t use candles anymore, and stuffing them into sensitive electronics is a terrible idea, so it’s sort of hard to tell how many of them you want in your screen without looking at a few numbers. As a general rule, more nits are always better, so if everything else is equal, you can’t go wrong with higher numbers. As long as you don’t max out your brightness when you don’t need to, it won’t have any negative effect on your battery.
Here’s a breakdown of the max nit capabilities you should look for.
Smartphones/tablets: 200 to 1000+ nits
Since they’re commonly used outdoors, smartphones are definitely in the “more nits are better” category. Technically, a device starts counting as “sunlight-readable” when it hits at least 1,000 nits, but very few mobile displays go that high. As a general rule, anything above 400 to 500 nits will do pretty well on a sunny day, but at 200 nits, you might have to find some shade to answer texts.
Laptops/monitors: 200 to 600+ nits
Laptops and PCs are mostly indoor creatures, so they don’t need to be as bright. 200 is on the low end but still usable, while above 400 is above average. Not many computer displays go above 500 or 600 nits, and you probably won’t need to use the full brightness on one of those very often. Again, though, you can’t go wrong getting more nits if you have the option to.
TVs: 100 to 2000+ nits
Older TVs probably fall in the ~100-nit range, but most modern non-HDR displays fall in the 200 to 500 range. HDR TV works best with high nit counts and generally requires a minimum of 500, with a lot of models aiming for at least 700. Higher-end HDRs can be 2000 nits or more.
How much do nits really matter?
Nits are important but shouldn’t be the one deciding factor in your screen choice unless you specifically need something above a certain level of brightness for HDR or outdoor use. Resolution, contrast ratios, black levels, sRGB color, and other factors also affect your screen quality, and as long as you’re not on the far low end of the nit range, you’re probably fine. The most important thing is just knowing what a low, medium, and high nit number looks like for a given device so you can make an informed decision.