first of all: df -h does some severe rounding on the real values, so you shouldn't rely on it. if you are really interested in the exact values, use df -k and do the math by hand.
second: these statistics can (and will) show confusing numbers when you are looking on a freshly installed system, because statistics will always fail on small numbers, so unless you're running the system for at least a day or so, these numbers will never be reliable - they will not even be reasonable.
first of all: df -h does some severe rounding on the real values, so you shouldn't rely on it. if you are really interested in the exact values, use df -k and do the math by hand.
second: these statistics can (and will) show confusing numbers when you are looking on a freshly installed system, because statistics will always fail on small numbers, so unless you're running the system for at least a day or so, these numbers will never be reliable - they will not even be reasonable.