1 litre is defined as 1000 cubic centimeters.
You should be able to use this to get what you want.
I think you might be going about it the wrong way.
0.5 ft = 15.24 centimeters.
You need to work out what 0.5 cubic feet is in liters.
1 ft = 30.48 cm, so 1 ft^3 = 30.48 * 30.48 * 30.48 cubic cm.
I think you are confused, although 1ft * 1ft *1ft is 1 cubic ft (1ft^3), 0.5 ft * 0.5 ft * 0.5ft is not 0.5 cubic feet (its 0.125) so converting 0.5ft to cm and cubing it won't work.
What you need to do is find the cube root of 0.5, convert that into centimeters and then cube that.
This is really annoying me,
how do i convert
0.5ft^3 into L