Type K thermocouple table: mV vs °C (−270 to 1372 °C)

Type K thermocouple voltage in mV from −270 to 1372 °C in 10 °C steps, from the NIST (ITS-90) reference functions with the reference junction at 0 °C.

A type K thermocouple (nickel-chromium (+) and nickel-aluminium (−)) 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 K thermocouple, reference junction at 0 °C: −270 … 140 °C
°C	mV
−270	−6.458
−260	−6.441
−250	−6.404
−240	−6.344
−230	−6.262
−220	−6.158
−210	−6.035
−200	−5.891
−190	−5.730
−180	−5.550
−170	−5.354
−160	−5.141
−150	−4.913
−140	−4.669
−130	−4.411
−120	−4.138
−110	−3.852
−100	−3.554
−90	−3.243
−80	−2.920
−70	−2.587
−60	−2.243
−50	−1.889
−40	−1.527
−30	−1.156
−20	−0.778
−10	−0.392
0	0.000
10	0.397
20	0.798
30	1.203
40	1.612
50	2.023
60	2.436
70	2.851
80	3.267
90	3.682
100	4.096
110	4.509
120	4.920
130	5.328
140	5.735

Type K thermocouple, reference junction at 0 °C: 150 … 560 °C
°C	mV
150	6.138
160	6.540
170	6.941
180	7.340
190	7.739
200	8.138
210	8.539
220	8.940
230	9.343
240	9.747
250	10.153
260	10.561
270	10.971
280	11.382
290	11.795
300	12.209
310	12.624
320	13.040
330	13.457
340	13.874
350	14.293
360	14.713
370	15.133
380	15.554
390	15.975
400	16.397
410	16.820
420	17.243
430	17.667
440	18.091
450	18.516
460	18.941
470	19.366
480	19.792
490	20.218
500	20.644
510	21.071
520	21.497
530	21.924
540	22.350
550	22.776
560	23.203

Type K thermocouple, reference junction at 0 °C: 570 … 980 °C
°C	mV
570	23.629
580	24.055
590	24.480
600	24.905
610	25.330
620	25.755
630	26.179
640	26.602
650	27.025
660	27.447
670	27.869
680	28.289
690	28.710
700	29.129
710	29.548
720	29.965
730	30.382
740	30.798
750	31.213
760	31.628
770	32.041
780	32.453
790	32.865
800	33.275
810	33.685
820	34.093
830	34.501
840	34.908
850	35.313
860	35.718
870	36.121
880	36.524
890	36.925
900	37.326
910	37.725
920	38.124
930	38.522
940	38.918
950	39.314
960	39.708
970	40.101
980	40.494

Type K thermocouple, reference junction at 0 °C: 990 … 1372 °C
°C	mV
990	40.885
1000	41.276
1010	41.665
1020	42.053
1030	42.440
1040	42.826
1050	43.211
1060	43.595
1070	43.978
1080	44.359
1090	44.740
1100	45.119
1110	45.497
1120	45.873
1130	46.249
1140	46.623
1150	46.995
1160	47.367
1170	47.737
1180	48.105
1190	48.473
1200	48.838
1210	49.202
1220	49.565
1230	49.926
1240	50.286
1250	50.644
1260	51.000
1270	51.355
1280	51.708
1290	52.060
1300	52.410
1310	52.759
1320	53.106
1330	53.451
1340	53.795
1350	54.138
1360	54.479
1370	54.819
1372	54.886

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