Hygrometer calibration question

[SeaHen]

I have a digital Springfield thermometer/hygrometer that I've been attempting to calibrate for the last two days using the salt-and-water-in-a-coffee-cup method. The highest consistent reading I've gotten is 65%, and that's from two different locations. Should I really assume it's off by 10%? Has anyone else had this low a reading during calibration?

 

[Kittymomma]

I have one that is off by four and the other one (digital) is off by nine. I know it can be hard to believe, but it's not uncommon for them to be off by that much.

 

[SeaHen]

Thanks, I feel better now!