Jerry has this one right for sure.

I deal with instruments everyday so I tend to use them as a crutch. I am also crazy fussy with them I will accept 5% up or down but I really want less than 1%. I don't have the ability to calibrate to this accuracy, the salt tests are only to 1% +/-.

I have been trying to learn to let it go and have managed to not toss a thermometer that when tested today was 1.2ºF high.

Ok I just did toss it. I really should not write in posts like this my standard is too high un reasonable for most to manage. The accurite is likely fine just keep in mind it is likely off by a bit and plan according say set the hot spot to be 91 and if it is high be a degree or two it is still fine same for a degree or two low. Assume it is within a 3 or 4 degree range and set based on this. Same for the hygrometer (40-80% can't even think about that) if the snake sheds it is good.