IR guns are all about the same accuracy about 2ºF+/- Personally I would avoid any that are specs say worse than this (2ºC +/-) past that I would look at the D:S ratio and the type of battery. I like to use units that take common batteries I had one a while ago that took 8 SR44 at 6$ each it was a killer. The DS ratio is the related to how large the measuring circle is at a given distance. It also relates to the optimal measuring distance for best results. The typical for royals is DS 1:1 with a optimal measuring distance of 4 inches at 6:1 it is 24 inches.

I do not like accurites at all. I have not found them to be better than any other or ever very accurate at all. I have owned three and all three were high in temps two were outside the specs and returned and one just barely inside and given away. I have been told recently that some of their units are spec at +/-2ºC that is very close to 4ºF IMO this is too much to be useful.

There are very few ways to be certain a unit is accurate one way is to buy a traceable unit that states it is a particular accuracy and has tests to confirm this. These with a decent accuracy (+/-1ºF) are often very expensive, more than most budgets. (run in the 300-1200$ range) This leaves a whole range of poor digital units that are cheap. I suggest buy a handful (at least 3 but more are better personally I buy 10-20 at a time) then test them against each other. Typically they will vary up and down from each other. The average is often close to correct and the ones that are off from the majority can be assumed are incorrect and discarded. Clearly this is an issue with accurites as well as 20 11$ units you could have bought a good unit in its place. I usually buy the cheapest I can find. They usually are the single probe aquarium ones I often find them for 1$-3$ with shipping each. Ebay is a good place for these.


Hygrometers I'd go with analogue ones intended for cigar boxes. They are cheap and accurate as well as calibratable a simple salt test will indicate the RH to 1% much better than the typical 5-10% error some digital units have (accurites are either 5% or 15% depending on the unit) They are easily available on amazon usually having a glass face and brass body with a poor magnetic attachment that often needs to be tinkered with (re glueing the disk and a better magnet)