Primary Standards Lab, Sandia National Laboratories

The Sandia Uncertainty Calculator (Suncal) is developed by the Primary Standards Lab at Sandia National Laboratories to calculate the combined uncertainty of a system of multiple input parameters.

In general, a measurement value is calculated from a function of several input measurements: Y = f(x1, x2, x3…). Each input X value has a measured value and associated uncertainty. This calculator will determine the total uncertainty in the output quantity Y. Two approaches are used, the Kline-McClintock uncertainty approximation as described in the Guide to Expression of Uncertainty in Measurements (GUM), and a Monte-Carlo method.

Other features include risk analysis (probability of false accept and reject), analysis of variance, and finding uncertainty in curve fitting.

Desktop version

Download binaries for Windows and Mac OSX, along with a user manual and some usage examples, from the Latest Release page.

Online version

Some features of Suncal may be run through the Web Interface to Suncal, an online interface without any download or installation required.


Uncertainty Output

Joint PDF output

Curve Fitting

Risk Analysis


Please report any issues on the issue tracker.

Copyright 2019-2023 National Technology & Engineering Solutions of Sandia, LLC (NTESS). Under the terms of Contract DE-NA0003525 with NTESS, the U.S. Government retains certain rights in this software.

This software is distributed under the GNU General Public License.