Any load cell can be a calibration class load cell provided that:

• Its uncertainty is known.

• It is used to calibrate load cells, whose uncertainty only needs to be four times more (the generally-accepted ratio) than this calibration standard.

• It is only used over part of its measurement range (say 20% to 100%), which is dictated by the uncertainty of the cell.

For example: A 1,000 lb load cell with an uncertainty of 0.5 lb, which means that if it measures a load and it indicates 760 lbs, it could actually be anywhere between 759.5 lbs to 760.5 lbs. This load cell is used as a reference standard to calibrate other load cells, provided that these cells under test are not required to report loads with a greater uncertainty of +/- 2 lbs. In addition, this reference cell would not be able to carry out calibrations with loads less than 200 lbs. This lower limit is determined by multiplying the uncertainty by 400 for class A load cells and 2,000 for class AA load cells.