Maker Label Studio

Measurement Uncertainty Budget Builder

Calculate combined and expanded measurement uncertainty following JCGM 100 (GUM).

Global Parameters

Typically k=2 for ~95% confidence level.
Used to calculate guardbanded acceptance limits.

Uncertainty Components

Source / Description Value (±) Distribution Divisor Sensitivity (c_i) Actions

Results & Propagation

Combined Std. Uncertainty (u_c)
0.00
Expanded Uncertainty (U)
0.00

Component Contributions

Source Std. Unc. (u_i) Variance (c_i * u_i)² Contribution %

Calibration Statement

Enter components to generate a statement.

Developer / QA Self-Tests

About the Measurement Uncertainty Budget Builder

Metrology professionals and calibration laboratories rely on this measurement uncertainty budget builder to definitively quantify confidence in analytical results. It systematically evaluates both Type A and Type B components to calculate combined standard uncertainty and expanded uncertainty using the proper coverage factor, ensuring your laboratory maintains strict compliance with ISO/IEC 17025 standards.

How it works

  1. Enter the base measurement value and its relevant unit of measure.
  2. Input Type A uncertainty components derived from statistical analysis of repeated observations.
  3. Add Type B uncertainty components from calibration certificates, manuals, or environmental factors, selecting the appropriate probability distribution.
  4. Set the desired confidence level (typically 95%, k=2) to calculate the final expanded uncertainty.

Frequently asked questions

What is the difference between Type A and Type B uncertainty?

Type A uncertainty is evaluated by statistical methods from a series of repeated observations. Type B uncertainty is evaluated by other scientific means, utilizing calibration certificates, manufacturer specifications, or assumed probability distributions.

How do I choose the correct probability distribution for Type B?

Use a normal distribution for calibration certificate data, a rectangular distribution for manufacturer tolerances or digital resolution limits, and a triangular distribution when values are more likely to lie near the center of a specification limit.

What is a coverage factor (k)?

The coverage factor is a mathematical multiplier used to convert combined standard uncertainty into expanded uncertainty. A factor of k=2 typically represents an approximate 95% confidence interval for a normal distribution.

Why is an uncertainty budget required for ISO 17025?

ISO/IEC 17025 requires testing and calibration laboratories to evaluate and formally report measurement uncertainty to prove their analytical equipment and methods are capable of producing valid, traceable results.

References