First you should accurately measure left and right sides at a couple of places to accurately measure the difference in heights. Next you might get it weighed on all 4 corners to see if one side weighs more than the other. If a weight difference doesn't explain it, you'll need to have the springs examined. The low side might have a broken or bent spring.
Bob & Donna
'98 Gulf Stream Sun Voyager DP being pushed by a '00 Beetle TDI