Calibration · Glossary

What is Total Probable Error?

Symbol: TPEcombined installed errorCalibration

Total probable error combines independent error sources, such as reference accuracy, temperature and static pressure effects, by root sum of squares.

Total Probable Error Explained

Adding all errors directly gives a worst case that rarely happens. Root sum of squares gives a more realistic estimate when errors are independent.

TPE is used to compare transmitters and to set realistic calibration tolerances.

Total Probable Error Formula

TPE = √(e₁² + e₂² + e₃² + …)

e_i	individual errors in the same units

Example: 0.065 %, 0.10 % and 0.05 %: TPE ≈ 0.13 %.

Calculators for Total Probable Error

CalculatorTotal Probable Error CalculatorFree online calculator with formula and worked example.CalculatorAccuracy Specification CalculatorFree online calculator with formula and worked example.

Free Downloads

Free downloadTransmitter Accuracy Calculation ExcelFree download in Excel and PDF.

Frequently Asked Questions

What is Total Probable Error?

Total probable error combines independent error sources, such as reference accuracy, temperature and static pressure effects, by root sum of squares.

When should errors be added directly?

When they are correlated or for a strict worst case.

Does TPE include drift?

Include stability over the calibration interval if relevant.

Learn more on the blog

Instrumentation calibration and troubleshooting guide

A practical guide on instrumentationblog.in with more detail on total probable error and how it is applied on real plants.

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More Calibration Terms

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