Bests & Worsts Reviews from Amazon

A cap full of salt in a baggie with your hygrometer will give you the plus or minus that your hygrometer is off. That's all you need to know to be accurate with your readings. The salt is always 75%. If your hygrometer reads 82%, then its reading +7. Simply subtract 7 from your hygrometers reading to get the actual humidity. It's really that simple. Cheers