We have a new forum and it needs your help! Homebrewing Deals is a forum to post whatever deals and specials you find that other homebrewers might value! Includes coupon layering, Craigslist finds, eBay finds, Amazon specials, etc.
None of the SG hydrometers I have found are calibrated to 20C. I have been thinking about a method or methods to do this conversion, but can't try them without, for example, both gravities for a 10P solution.
The more complicated nerdy method starts with equality of mass of extract (wex):