Are there any good reasons for using hex over decimal for RGB colour values in CSS?

Question

rgb(255,255,255) notation has been available since CSS1. But #ffffff seems to be vastly more popular.

Obviously it's slightly more compact. I know that hex is more closely related to the underlying bytes, and understand that there would be advantages in carrying out arithmetic on those values, but this isn't something you're going to do with CSS.

Colour values tend to be originated by designers (such as myself) who would never encounter hex notation anywhere else, and are much more familiar with the decimal notation which is the main way of specifying colour in the apps they use -- in fact I have met quite a few who don't realise how a given hex value breaks down into RGB components and assumed it didn't directly relate to the colour at all, like a Pantone colour system reference (eg PMS432).

So, any reason not to use decimal?

Solution 1

Hex values are easier to copy and paste from your favourite image editor.

RGB values are easier to manipulate with Javascript.

(My favourite Hex colour value is #EDEDED and a site we made for a client involved in motorsport had a background colour of #F1F1F1 :-)

Ed.

Solution 2

It's worth noting that if you want to input an RGBA value, hex notation is not supported; i.e., you can't fake it with #FFFFFFff. As a matter of fact, the alpha value must be a number between 0.0 and 1.0, inclusive. (Check out this page for browser support -- as always, IE is leading the pack here. ;) )

HSL and HSLA color support -- which is very designer friendly -- is also provided with a similar syntax to the RGB() style. If a designer were to use both types of color values in the same stylesheet, they might opt for decimal values over hex codes for consistency.

Solution 3

I think it's what you're used to. If you're used to HTML, you'll probably use HEX since it's just been used a lot in HTML. If you're from a design background, using Photoshop/Corel/PaintShopPro etc., then you're likely used to the RGB notation - though, a lot of programs these days incorporate a HEX value field too.

As said, RGBA might be a reason to just go with the RGB notation - consistency.

Though, I think it also depends on the scenario. If you're comfortable with both, you might just switch between them: #fff is a lot easier to type than rgb(255,255,255).

Another question is why people will say #fff instead of White (assuming most browsers support this keyword).

It's all a matter of preference and legibility - if you're maintaining a huge CSS file, being able to look at the colour value and know what colour it is, is a really good advantage. Even more advantageous is using something like LESS or Sass to add a kind of programmability to CSS - allowing constants for example. So instead of saying:

#title { color: #abcdef; }

You might instead do the following with LESS:

@base-color: #abcdef;

#title { color: @base-color; }

Maintaining the CSS becomes less of an issue.

If you're worried about the performance of the browser rendering it's result, then that could also be another factor to your choice.

So in summary, it boils down to:

• Familiarity
• Preference
• Maintainability
• Performance

Solution 4

The main reason is probably compactness, as you mentioned. #ffffff can even be further shortened to the #fff shorthand notation.

Another possible reason is that there's a perceived performance increase by saving the browser the trouble of converting the rgb notation.

Solution 5

I always used hex, but today I prefer to set my values as:

rgb(82, 110, 188)

in my css files, so whenever I want to add opacity I just need to rename rgb to rgba and add the opacity value. The advantage is that I don't have to convert the hex value to rgb before being able to add the opacity:

rgba(82, 110, 188, 0.5)

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Comments

[tnyfst]

Well, it's usually 6 characters. It can also be 3 characters.

[Admin]

As RGBA becomes more widely used (it is quite useful), I expect a resurgence of usage of decimal notation. Good point!

[Guffa]

The shortened format doesn't automatically give you web safe colors. You have to limit the component values to 0,3,6,9,C and F to get the 216 web safe colors.

[Isabelle Wedin]

The nice thing about HSL is that you can easily make up matching color schemes on the fly and have a pretty good idea of what they'll look like before you even refresh the page. There's no need to open up Photoshop to pick out three shades of the same red. Even complimentary colors are easy to pick out; 120 degree rotations are trivial in RGB, but I'm not sure if 180 degrees can be calculated so readoily.

[Elzo Valugi]

I don't get the down vote.. rgb(255,255,255) is way longer than #fff. This is the touch of speed I was talking about.

[jamiebarrow]

"number x = 255" is more intuitive to the way people are taught maths than "number x = #f". and to people who aren't even mathematically inclined "255" is even more intuitive. abstracting over the machinery is meant to improve human insight into what's going on. having said that, to me, #fff is just as intuitive as rgb(255,255,255). and because im lazy i'll use #fff :)

[Ricardo Zea]

In Sass you can still use HEX values and combine them with alpha. For example: .container { background: rgba(#369, .2); }. Here's a Demo in JSFiddle.

[Rick]

There is a perceived performance difference? I had a double take on your comment to check if it was written before 1991. Is this based on any data?

[underscore_d]

LMAO. A thought experiment for anyone who thinks they are "saving the browser the trouble": Do you think computers natively consume hexadecimal values encoded as ASCII, any more than they do decimal ones? In either case, the browser must convert the ASCII strings to the 8-bit numbers that the rendering engine needs. Plus, any size advantage of hex colours will not matter in any non-contrived scenario.

[underscore_d]

A touch of speed that is so unlikely to be significant in any practical situation that it is hardly worth mentioning, especially as the leading reason.

[Bill the Lizard]

@underscore_d You act like all browsers are created equally.

[Darren Griffith]

The CSS Color Module Level 4 draft spec adds the 8-digit hexadecimal notation #RRGGBBAA and #RGBA. According to caniuse, such notation is supported by 76% of browsers (in Sept 2018), with no IE or Edge support yet, so it not advisable to use... yet.

[Darren Griffith]

The CSS Color Module Level 4 draft spec adds the 8-digit hexadecimal notation #RRGGBBAA and #RGBA. According to caniuse, such notation is supported by 76% of browsers (in Sept 2018), with no IE or Edge support yet, so it not advisable to use... yet.