You take the reading you get from the salt test,/calibration and either add or subtract the % diff from the standard (75%) from the current reading in the bator to determine the % humidity. Ex: calibrated hyrometer reading 67% RhOmg. I can't get caught up. . but @KikisGirls
Your hygrometer/thermometer looks almost like the one I just bought. . and the humidity only read 67% during the salt test instead of 75% like it should.
I bought another digital one that's for reptiles and it doesn't read correctly either.
Luckys eggs weren't blue![]()
75 - 67 ÷ 75 × 100 = -10.66% Rh or rounding up -11% Rh. so true Rh would be 78% Rh. If you have a higher reading, 75 - 82 ÷ 75 × 100 = 9.33%, so your hygrometer is reading 11% low. You would add 11% to whatever your monitor is reading in the bator or in the example you subtract 9%Rh from your reading to get the true % humidity. HTH