Thermometer Accuracy

I use a plain old floating thermometer for checking all my temps while brewing. While reading another thread on here today, I decided I needed to check my thermometer for accuracy. So, I boiled some water and held it in there while it boiled. It topped out at 206* at a rolling boil. So I did a little digging, and found out that water boils at lower temps in higher elevations(2*per 1000ft) and I live at about 2300ft. So according to that,my water should boil at around 207*. In theory, my Thermometer reads 1* low.

Does that sound accurate or am I off 6*?

I suppose i shouldn't sweat it since I usually get about 75% efficiency, my highest being 80% so far. That tells me I'm getting decent conversion.

Thanks,Mike

The correct way to calibrate is crushed ice and water mixture. 32 deg

The best way to calibrate is to get one of these. Your thermometer may be dead on at boiling and freezing, unfortunatly, you aren't mashing at boiling or freezing. You need to make sure it reads right at 150-160.
Heat some water to 150, put both thermometers in the water, and trust the lab thermometer.
It's the best method I found so far. (It's also the method used by QA at a sausage plant I used to work at, for whaterver thats worth)