I'm making GUIs and on my smaller monitor it covers the whole thing, but on my bigger one it covers only half. Is there a way to detect how big your monitor is and setting your Gui to cover the whole screen? Does the ROBLOX wiki explain this?
Just use Scale to size your GUIs and it will remain consistent throughout all monitors. If you don't know what Scale is or how to use it, you can check out this similar question I answered. The Roblox WIki doesn't go too in-depth about Scale in their UDim2 article, but if it helps, you can read it here.
There isn't exactly a way to detect the dimensions of the client's screen, but there's an alternative.
Using the Scale argument while setting the UDim2 dimensions of a gui, rather than using Offset.
The Scale argument is the first number inside the brackets, the Offset is the Second number.
So say you have this;
gui.Size = UDim2.new(0,200,0,200)
To make it the same for all screen sizes you can do this(estimated);
gui.Size = UDim2.new(.2,0,.2,0)