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What is a type K Thermocouple?

A Type K thermocouple refers to any temperature sensor containing Chromel and Alumel conductors, that meets the output requirements as stated in ANSI/ASTM E230 or IEC 60584 for Type K thermocouples. This may be an immersion sensor, a surface sensor, wire or another style of sensor or cable.

What are the Typical Color Codes for Type K Thermocouples?

Type K wire is primarily available in two color-codes, yellow connectors and/or yellow and red conductors per ANSI/ASTM E230, or green Connector and/or green and white conductors per IEC 60584.

Click on this link to check the complete thermocouple color code chart

Alloy Combination
Color Coding  
Maximum Useful
Range ++
Thermocouple Grade
EMF (mV)
Over Max.
Standard Limits
of Error**
(above O°C)
Limits of Error**
(above O°C)
IEC 584-3
Environment —
Bare Wire
+ Lead - Lead Thermocouple
Thermocouple Grade:
–328 to 2282°F
–200 to 1250°C
Extension Grade:
32 to 392°F
0 to 200°C
–454 to 2501°F
–270 to 1372°C
–6.458 to
greater of
2.2°C or 0.75%
greater of
1.1°C or 0.4%
Clean Oxidizing and Inert.
Limited Use in Vacuum or
Reducing. Wide Temperature
Range, Most Popular Calibration

++ Except as further restricted by temperature limits for T/C diameter and insulation tables that follow.

* Not official symbol or standard designation.

** For controlled initial accuracy below 0°C, ask OMEGA's sales Department for a CAL-4 calibration report.

Temperature Ranges for Type K Thermocouples

Type K thermocouples have a general temperature range of -200 to 1260°C (-326 to 2300°F), however there are some caveats to this:

  1. If used for temperatures below 0°C special material is needed in order to meet the specified accuracies. Also, Special Limits of Error are not specified for temperatures below 0°C.
  2. The ultimate suggested upper temperature limits for Type K are based on the size of the conductor used:
Wire Gage Diameter Maximum Suggested Temperature
#8 AWG 0.128” 1280°C/2300°F
#14 AWG 0.064” 1090°C/2000°F
#20 AWG 0.032” 980°C/1800°F
#24 AWG 0.020” 870°C/1600°F
#28 AWG 0.013” 870°C/1600°F
#30 AWG 0.010” 760°C/1400°F

Temperature Ranges for Type K Thermocouples

The following is a selection of output values for Type K Thermocouples at selected temperatures. Note: The following output is based on a reference Junction at 0°C/32°F:

Temperature Output
0°C 0.000 mV
100°C 4.096 mV
200°C 8.138 mV
300°C 12.209 mV
400°C 16.397 mV
500°C 20.644 mV
600°C 24.905 mV
700°C 29.129 mV
800°C 33.275 mV
900°C 37.326 mV
1000°C 41.276 mV
1100°C 45.119 mV
1200°C 48.838 mV

Resistance Chart for Type K Thermocouples

Thermocouples are not manufactured to a specific resistance, they measure temperature based on the output voltage they provide. Resistances will vary with conductor size and somewhat with the lot of conductor used.

How Much Do Type K Thermocouples Cost?

The cost of a Type K thermocouple will depend upon the style of the sensor you choose. Once you determine what style sensor you need you can find pricing on our website at If you need assistance in selecting the thermocouple you need, please contact our Application Engineering staff who can assist you in your selection.

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