We provide a universal calibration of the W5%Re vs W26%Re (type-C) thermocouple alloy which may be used in the temperature range of 32-2588 K. Our calibration is within the limits of standard error reported by Omega [The Omega Complete Temperature Measurement Handbook and Encyclopedia (Omega Engineering, Stamford, CT, 1989), pp. z8-z28] for their data in the temperature range of 255-2588 K, and rationally extends the calibration downward in temperature.