I bought a Wixey WR365 magnetic digital angle gauge at my local Rockler store. It is very accurate, to 0.1 degrees. I chose the WR365 because it also has an "earth level" like an ordinary bubble level, but with the same 0.1 degree precision. It does both relative angle and earth level angle. It also has a tilt display for readability, but the tilt display is not that important or useful to me. It does not have a backlight, which would have been nice.
Rockler also carries the Wixey WR300 angle gauge. It has a backlight, but no earth level and no tilt display.
To use one, place it on the table saw table, zero the angle, then place it on the blade and the tilt the blade until the desired angle appears on the display.
You can find similar magnetic angle gauges from other sources. As far as I can tell, they are all essentially the same. They are very accurate and repeatable, and are well worth the money. You will find many more uses for them, trust me. I would look for the features you want, then shop for price. It is as simple as that.
Last edited by Tool Agnostic; 07-16-2020 at 10:20 AM.