Garage door weight is determined by size material steel gauge thickness insulation and glass.
How much wight garage door.
Door weight is important when trying to figure out what torsion or extension springs are needed to counterbalance the door.
Based on this rating a 1 2 hp opener be able to lift about 185 pounds and a 3 4 hp opener should be able to lift over 370 pounds.
How much weight can a garage door opener lift.
Therefore you need a pair of 210 pound springs even though your total door weight is 210 pounds.
It should be noted that since the cable loops around a pulley the lifting force of a 210 pound spring is only 105 pounds as seen by the garage door.
If you have a heavier door that weighs more than 150 pounds with one spring still wound you will need to use 2 scales and position them under the first row of hinges from each end of the garage door.