Be careful, most digital thermometers (GOOD ones) are only accurate to +/- 0.3%, percent NOT degrees. And these are NOT the under $20 ones. Many of the cheaper ones are accurate to less than 3%.(posted 8615 days ago)There are two things, absolute accuracy and repeatability. Absolute accuracy is what you check when comparing it to a high quality glass thermometer. But if it isn't repeatable, everytime you use it, it will give you a difference answer.
The BEST is the Kodak Process Thermometer. It is glass, but in a SS sleeve to protect it very well.
I looked at digital, including high end (over $300) ones, and they just aren't there.