You cut off the legs leaving at least 1 1/2 inches longer then you would like the shorts to be. If I'm not mistaken you want the shorts to be just above the knee. Measure 1 1/2 inches longer to hem. Fold over 3/4 in. and fold again to hem.
If you cut your pants below the knee but above the calf, the would be bermuda short length. If you cut jeans you would be able to allow the bottom to frey and it will have the distressed look. You could also hem the bottom for a cleaner look.
You can turn pants into bermuda shorts very easily! First you put the pants on and measure where the pants are approximately at the the knee. Mark this area off with a pen. Then you take the pants off and cut them the you measured them. Tada! Bermuda shorts that you already know fit perfectly!