This is always a concern when designing a website. You don’t want your website to be too wide, which forces your visitors to scroll horizontally, because that’s annoying. You also don’t want it to be too narrow and to waste valuable real estate on the screen.
A few years ago, it was a good rule of thumb to create a website that would automatically fill the whole screen. But, a few years ago, most monitors fell within the 15” to 17” size range – you’d occasionally see a 19” monitor, but it was very rare to see anything larger than that.
Now, it’s much more common to have very large monitors. 20” monitors are very affordable, and monitors up to 30” are available. If you design your website to scale up to fit the screen, then your website will be huge on these big monitors. Your body copy will also scale to have extremely long lines of text, which can be very difficult to follow across the page and read easily.
To avoid this, you should plan to constrain the width of your web page. But, when choosing a width to use, you have to consider the opposite end of the monitor size spectrum – the smaller monitors that are out there, like laptop monitors. There are many laptops still with very small screens, and having even smaller screens
I recommend designing your website to be roughly 800 pixels across. This will seem small if you have a big monitor, but will ensure that everyone is able to see all of your valuable website content and that they can get the most out of your website.