Type T thermocouple table: mV vs °C (−270 to 400 °C)

Type T thermocouple voltage in mV from −270 to 400 °C in 10 °C steps, from the NIST (ITS-90) reference functions with the reference junction at 0 °C.

A type T thermocouple (copper (+) and copper-nickel, constantan (−)) produces a voltage that depends on the temperature difference between the measuring junction and the reference junction. The table follows the NIST (ITS-90) reference functions, with the reference junction at 0 °C.

Type T thermocouple, reference junction at 0 °C: −270 … 140 °C
°C	mV
−270	−6.258
−260	−6.232
−250	−6.180
−240	−6.105
−230	−6.007
−220	−5.888
−210	−5.753
−200	−5.603
−190	−5.439
−180	−5.261
−170	−5.070
−160	−4.865
−150	−4.648
−140	−4.419
−130	−4.177
−120	−3.923
−110	−3.657
−100	−3.379
−90	−3.089
−80	−2.788
−70	−2.476
−60	−2.153
−50	−1.819
−40	−1.475
−30	−1.121
−20	−0.757
−10	−0.383
0	0.000
10	0.391
20	0.790
30	1.196
40	1.612
50	2.036
60	2.468
70	2.909
80	3.358
90	3.814
100	4.279
110	4.750
120	5.228
130	5.714
140	6.206

Type T thermocouple, reference junction at 0 °C: 150 … 400 °C
°C	mV
150	6.704
160	7.209
170	7.720
180	8.237
190	8.759
200	9.288
210	9.822
220	10.362
230	10.907
240	11.458
250	12.013
260	12.574
270	13.139
280	13.709
290	14.283
300	14.862
310	15.445
320	16.032
330	16.624
340	17.219
350	17.819
360	18.422
370	19.030
380	19.641
390	20.255
400	20.872

What about the cold junction?

In the field the reference junction sits at the transmitter or instrument terminals, almost never at 0 °C. So the voltage measured at the terminals is not the table value: the instrument compensates the cold junction. To check a mV reading, take the terminal temperature into account.

Calculated reference values, not measurements. The thermocouple tolerance depends on its class (IEC 60584-1) and is not in the table.

Values calculated from the reference functions; they do not replace measurement or a calibration certificate.

What about the cold junction?

See also