Calibrate a hygrometer?

[Mark kim]

i put a cup with salt and water mixed. my hygrometer read 65% so does that mean it is always 10% under? so if it reads 45% its 55?

 

[jafo]

http://exoticpets.about.com/od/herpresources/ss/hygrometer.htm

 

[joebryant]

Quote:
The printable instructions on step 8 is what I always use. Works great!

 

[joebryant]

Quote:
If you followed the instructions given in Jafo's reply URL, then yes, your reading of 45% would actually be 55%.

 

[Mark kim]

thanks for the help