Reference · updated 10 November 2026
Type K thermocouple table: mV to °C
A type K thermocouple (nickel-chromium against nickel-aluminium) makes a small voltage that depends on the temperature difference between its measuring tip and the point where it connects to the instrument. This page lists that voltage in millivolts for −200 to 1370 °C in 10 °C steps, with the reference junction at 0 °C. Every value is calculated from the NIST ITS-90 polynomials when the page is built; none is typed in by hand, and the build stops if five reference values are off.
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Type K thermocouple table
The values are the thermoelectric voltage E for a reference junction held at 0 °C. Find your voltage and read the temperature, or interpolate between two rows. Negative values are marked with a minus sign.
| Temperature (°C) | Voltage (mV) |
|---|---|
| −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 |
| 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 |
| 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 |
| 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 |
How the numbers are calculated
NIST gives the voltage of a type K thermocouple as a polynomial in the temperature t (ITS-90, in °C, E in mV). Below 0 °C: E = c0 + c1·t + c2·t² + … + c10·t¹⁰. From 0 °C up to 1372 °C the same kind of polynomial (c0 to c9) is used, plus an extra term a0 × e^(a1 × (t − a2)²). The coefficients are in the NIST ITS-90 thermocouple database; this page uses the numbers published there for type K, with a0 = 0.1185976, a1 = −1.183432 × 10⁻⁴ and a2 = 126.9686.
Five values to check against any other chart: 0.000 mV at 0 °C, 4.096 mV at 100 °C, 20.644 mV at 500 °C, 41.276 mV at 1000 °C and −3.554 mV at −100 °C. The generator for this page checks exactly these five before it builds.
The table does not include the tolerance of a real thermocouple wire, which depends on its class and the maker. Read the data sheet of your probe for that.
How to use the table with a multimeter
A thermocouple does not measure temperature at its tip alone. The voltage it makes depends on the difference between the tip and the place where the two metals meet your instrument, the cold junction. The table assumes that the cold junction is at 0 °C. In real work it is at room temperature, so you must add the voltage that the cold junction itself stands for.
- Set the multimeter to a millivolt range with good resolution, and connect the thermocouple. Use the correct type K connector or compensating wire; copper test leads add a second junction.
- Measure the temperature at the instrument's terminals, the cold junction, for example 23 °C.
- Look up the table voltage at that temperature (the table is in 10 °C steps; interpolate between rows, or use the polynomial) and add it to your reading.
- Look the sum up in the table. The temperature you find is the temperature of the tip.
Many multimeters do all of this for you in their temperature function with a K probe, and show °C or °F directly. Use the table when your meter has no temperature function, when you want to check what it shows, or when you want to know what a given millivolt value means. The slope is about 0.04 mV per °C, so a range that resolves 0.01 mV gives steps of about 0.25 °C at best.
Worked examples
With cold-junction compensation. A type K probe, read on a millivolt range, gives 8.10 mV. The meter's terminals are at 23 °C, which stands for 0.919 mV. Add them: 8.10 + 0.919 = 9.019 mV. The table has 8.940 mV at 220 °C and 9.343 mV at 230 °C, so the tip is at about 222 °C. Without the compensation you would have read 8.10 mV, which the table puts at about 199 °C, 23 degrees too low.
Below zero. In a freezer the meter shows −1.50 mV with its terminals at 20 °C, which stands for 0.798 mV. The sum is −1.50 + 0.798 = −0.702 mV. The table has −0.778 mV at −20 °C and −0.392 mV at −10 °C, so the temperature is about −18 °C.
Read this live with a meter
To see a thermocouple reading in the app, connect a Bluetooth multimeter the app reads live, such as the OWON OW18B. The app decodes the meter's temperature function in °C and °F, and the big readout shows it with stable digits. To follow a temperature over time, record a time series and review the graph afterwards. If you read millivolts and want to apply the cold-junction correction yourself, a scaling rule y = k·x + b can add the offset to live readings and captures; the raw reading is kept next to the adjusted one.
The calculator in the app has preset formulas for Ohm's law and power, series and parallel, dividers, LED resistors, RC, dB and unit conversion, and Cal Box fills it from your live reading and recent captures. The app does not have a thermocouple table of its own today; this page is the reference. For a resistance sensor instead of a thermocouple, see the Pt100 resistance table.
Sources
- NIST ITS-90 Thermocouple Database, type K, coefficients c0 to c10, a0, a1, a2 of the reference function: srdata.nist.gov/its90/type_k/kcoefficients.html. The NIST server did not answer on 2026-11-10 (error 504), so the coefficients were read on that date from the Internet Archive copy of the same page, captured 2024-01-10. The generator file states this in a comment.
- The five check values are the type K reference values from the brief for this page; the polynomial reproduces each of them within 0.0005 mV (build check). They were not looked up separately in a printed NIST table.
What the app does here, and what it doesn't
| What it does | Plan |
|---|---|
| A large readout that shows which digits have settled; OL and UL are shown as OL and UL, never as a number. | Free |
| Log sessions hold captures and time-series recordings, and recording continues with the screen locked. | Free |
| Scale readings with a factor and an offset, for clamp adapters, shunts and probe dividers; the raw reading is kept. | Free |
| Presets for Ohm's law and power, series and parallel, dividers, LED resistors, RC, dB and unit conversion. | Free |
| Cal Box fills the calculator from your live reading and recent captures, and suggests Ohm's law. | Free |
Questions
What is the voltage of a type K thermocouple at 100 °C?
4.096 mV with the reference junction at 0 °C. At 500 °C it is 20.644 mV and at 1000 °C it is 41.276 mV.
How do I convert type K millivolts to temperature?
Add the voltage that the cold junction (the meter's terminals) stands for to your reading, then look the sum up in the table and read the temperature. Between two rows, interpolate in a straight line; the type K curve is nearly straight over 10 °C.
Why does a thermocouple need cold-junction compensation?
Because it makes a voltage from the difference between two temperatures, not from one. The table assumes the reference end is at 0 °C. If it is at 23 °C, the reading is lower than the table says by the voltage of those 23 °C, so you add it back.
Can I measure a type K thermocouple with a normal multimeter?
Yes, on a millivolt range, or with the meter's temperature function if it has one. Use the correct connector or compensating wire and know the temperature at the meter's terminals. The millivolt route gives you the voltage; the table, plus the correction above, gives you the temperature.
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