RejZoR 20 liters tells me literally nothing about its dimensions.

PowerPC People have been using liters for this literally for ages. Liters can stand for volume just as for weight, if you didn't know. 1 liter is either a kilogram or 1,000 cubic centimetres (a cube with 10 centimeters per side).

Caring1 Great, now you have to be a mathematician just to buy a case.

RH92 It tells me that this is a big f case for an itx system knowing that SFF cases around 7 to 10L do already exist !

But it does give you an easily comparable ballpark number to compare to other cases, vs. having to compare measurements in three dimensions. Once you're looking at more than one case, that becomes pretty much impossible to keep track of.1 liter=1kg? One liter of what? Water? Yes, absolutely. Oil? No. Milk? Not quite. Steel? Lol. Be specific, please. 1 liter does not in any way indicate weight, but (as is part of the point of the metric system) ease of conversion is built into it, so one liter of water equals one kilogram. Different masses have different densities, so you can't simply invent a measure of volume that also measures the weight of more than a handful of substances. That's not how physics work.The 1000 cm3/10x10x10cm cube measure is very useful, though, even if you're of the imperial persuasion. One liter is a 4"x4"x4" cube.No. This is excruciatingly simple, really. As PowerPC said above, this can be eyeballed within reason by pretty much any child in the metric-using world, and as explained above, the conversion to imperial is dead simple too. It's also reasonably easy to imagine, say, that cube cut in half and stacked, for things that aren't quite that cube-like.That's turning things on their head a bit. 7-10l cases are TINY, even for ITX systems, as long as they include space for a GPU. For ITX without a GPU, 7l is rather large. But for fitting standard components (i.e. not requiring 1u server PSUs or FlexATX), 7-10l is absolutely frickin' tiny. 20l is perfectly normal. You're talking as if 7-10l is normal, which it really isn't. Your mental image of 'normal' needs adjusting. Are there a few options in the ~10l space? Sure. But it's definitely not