What percentage of users is representative?

When designing screens in software (or Web sites) for users, what percentage of the users makes a representative amount to design for?

For instance, when my company makes a screen, we try to make it no wider than 760 pixels, as this is the correct width for a user at 800x600 with his browser maximized.

At what point can we start catering to users at 1024x768 instead of 800x600?

Right now, between 9% and 12% of our users are at 800x600, depending on which of our sites they’re looking at, according to Google Analytics. If the number is still around 10%, it seems like we should continue to design for them.

At what percentage should we stop designing for that category? Is it 5%? 3%? 1%?

I don’t see how there could be a factual answer to this. It depends how much you value your low-end customers. At what point did businesses stop providing hitching posts for customers’ horses?

And as for your higher end customers: how better can you serve them with the larger format? And what are your competitors doing?

Sites should never be designed for any browser or for any display ratio

They should be fluid so each person gets the same result.

The issue is more problematic, because most of the popular sites are still looking best at 800x600. But overall most sites are looking for a 1024x768. But just because there are tons more of these sites (mostly blogs) doesn’t mean you should go for that ratio.

Further you have to add in laptops which don’t have a 4:3 screen. I’ve seen a lot of laptop users with different screen sizes and they resize their browsers to 4:3 then use the extra space for running other things.

This is why you need a FLUID site. That is it expands and fills out the extra space.

You need to check it in Mozilla type (Firefox, K-Meleon), IE Type, and Opera type browsers to make sure they are looking good.

You site should look good in ALL sites. It’s only difficult to do when you try to get way too fancy. If you want you can put a simple Javascript that reads the users display resolutions and serves up a different CSS style sheet for each different resolution.

With mobile internet devices like the iphone and some netbooks becoming more popular, it’s possible the amount of users with small and/or “weird” resolutions might go up, not down the next couple of years.

The actual interface we’re talking about is the management console for an e-commerce store. I doubt many people will be using cell phones to manage their stores, but they might use a Netbook or something else with weird resolutions.