Michael, It sounds to me like you're making this altogether too complicated. Don't focus on the software; focus on the science. The size of the "degree" unit is the same for Kelvin and Celsius. (I.e., if the temperature changes by 1 degree K, it changes by exactly 1 degree C.) The only this that is different between Kelvin and Celsius is the zero point. For Kelvin, 0 degrees is absolute zero and there are no negative values of temperature. (Well, that's not quite right, but you'll never encounter the exceptions.) For Celsius, 0 degrees is the freezing point of water at sea level. To convert between Kelvin and Celcius, just add or subtract a constant. That constant has a value of 273.15. That is, you can make a dimensionally-safe conversion from Kelvin to Celcius by subtracting 273.15. Converting from Celsius to Kelvin by adding 273.15. Cheers, Rick Aurbach Aurbach & Associates, Inc. On Aug 15, 2013, at 9:24 AM, boost-users-request@lists.boost.org<mailto:boost-users-request@lists.boost.org> wrote: From: Michael Powell <mwpowellhtx@gmail.com<mailto:mwpowellhtx@gmail.com>> Subject: [Boost-users] [units] "Simple" conversion from Kelvin to Celsius Date: August 14, 2013 2:39:56 PM CDT To: "boost-users@lists.boost.org<mailto:boost-users@lists.boost.org>" <boost-users@lists.boost.org<mailto:boost-users@lists.boost.org>> Reply-To: "boost-users@lists.boost.org<mailto:boost-users@lists.boost.org>" <boost-users@lists.boost.org<mailto:boost-users@lists.boost.org>> Hello, It's been a couple of years since I've done any work with Boost.Units, and I am finding that I want to make a dimensionally-safe conversion from Kelvin to Celsius. I've got an I2C controller that reports in Kelvin, but I want to report it to the end-user in Celsius. The examples I am finding seem to "almost" fit the bill, but I am having a difficult time extrapolating a sane conversion. First, would help if I understood what the Boost.Units SI (my assumed base-system) base-temperature units were. I gather Fahrenheit? Or is it indeed Kelvin? I could be mistaken. Thank you... Regards, Michael Powell