Thermometer tolerance testing tool

According to IEC 60751 or ASTM 1137 accuracy classes

 14 August 2022



With this tolerance testing tool, you can check the accuracy of RTD sensors according to the standards IEC 60751 and ASTM 1137 and the accuracy class of your RTD sensor.

The tool will tell you if your sensor is still ok (PASS) or needs to be replaced (FAIL).

How to use the tolerance testing tool

First, you have to tell the tolerance testing tool what kind of RTD sensor you’re going to test. Therefore, fill in the following fields:

TAG number

If you want to keep a track record of present and future calibrations of your temperature sensor you should fill in the TAG number of your device. Select the field by clicking into the empty box, then type your TAG number. This number will be stated on the printout of the test results.

Test date

Enter the date on which the test will be performed. You can fill in the date in two different ways:


Select the standard to which the sensor is built. You can choose between IEC 60751 and ASTM 1137.


Select the accuracy class of the temperature sensor. The choice of accuracy class depends on the standard you have selected. The following choices are possible:

IEC 60751 Class AA
Class A
Class B
Class C
ASTM 1137 Class B
Class C

STD Accuracy

If you made a valid choice for the standard and its accuracy class, this field will automatically indicate the accuracy to be achieved. If you have chosen the wrong combination for the standard and the accuracy class, the text ‘ combination not defined ‘ will appear in this field.

Ref. T° (°C)

While performing the test, enter here the stabilized temperature indicated by the temperature bath or the reference temperature sensor.

UUT T° (°C)

UUT stands for Unit Under Test. The temperature indicated by the sensor being checked must be entered here.

Error (°C)

This is an automated field that calculates the temperature deviation of the tested sensor.
Error = UUT T° – Ref. T°

STD Err (°C)

This is an automated field that calculates the maximum allowable error according to the chosen standard and accuracy class. It uses the formula indicated in the STD Accuracy field in which it inserts the temperature of the test point entered in the field Ref. T°.


This is an automated field with only two possible outcomes: PASS or FAIL
When it says PASS, your sensor is good to go. If it says FAIL, your sensor is inaccurate and should be replaced.

Add test point

Click this button if you want to add another test point. The next test point will be added underneath the already indicated test points.

Print results

Click this button after you have completed all your test points. Your test results will be printed.


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