" 
 :Those are rounding errors. The template will round off itself to the number of digits in the input. For inch measurements that typically means 1 or 2 digits, thus 4 inches is converted to 100 mm rather than 102 mm and 12 inches to 300 mm rather than 305 mm. The thing to do is to force the template not to round at all by adding ""|0"" to it.  "