In 1 feet there are exactly 12 inches.
If something measures 12 inches then it also measures 1 foot long.
If something measures 6 inches then it measures 1/2 foot.
If something measures 24 inches then it also measures 2 feet.
And if something measures 36 inches then it measures 3 foot and if it measures 48 inches it measures 4 feet.
There will always be 12 inches in every feet when it comes to measuring something.