Basically, if you arent somekind of math prodigy, you are screwed :D
James has said that he used this: https://www.omega.com/temperature/Z/pdf/z198-201.pdf
for his calculations on app side.
Here is about same information in little bit easier to copy/paste to your spreadsheet:
I have used hours to figure that out and at some point, thought it was easier to just learn java and i checked mooshimeter-app sources to see how James did it.. And he had used some shortcuts, i was way deeper in that shit at that point :D (nist instruction says that we need to calculate reference temp to volts, then Vref+Vmeasured gives real temperature. I’m still planning to graph how much difference there is, but its already somewhat close in apps math channel)
And googling for those conversions gives about 20 different ways to do it, but every time it seems to have same origins at nist ( http://srdata.nist.gov/its90/download/download.html ). And almost every time, something has been lost and to get even close to desired values, they have had to add some “little” multiplications like x1000000 to their functions :D Surprisingly many sites have identical math for volts to celcius conversion, but instructions have randomly millivolts and microvolts in them.. And my head hurts, so i try to avoid thermocouples for few days ;D
So, its likely that no one really knows how to do k-type thermocouple measurements :D