The measurement reads out a value between 0% (opaque material such as cardboard) and 100% (pure air).
All Laser Labs, Inc tint meters are accurate within plus or minus 2% and are not affected by humidity or stray light. They are reliable from 0º to 100º F, day or night.
Two NIST traceable reference samples are included with each meter. The lighter sample is high transmittance (65% to 80%), and the darker sample is low transmittance (20% to 35%).