± Absolute Uncertainty Calculator
Convert between absolute and relative (percentage) uncertainty for any measurement. Enter your measured value and either form of uncertainty to get the other.
What This Calculator Does
Absolute uncertainty expresses how far a measured value could realistically be from the true value, in the same units as the measurement itself. This calculator converts a relative (percentage) uncertainty into an absolute uncertainty and shows the resulting measurement range.
The Formula
Absolute uncertainty is calculated as:
- Absolute Uncertainty = |Measured Value| × (Relative Uncertainty ÷ 100)
- The reported range is Measured Value ± Absolute Uncertainty.
Relative uncertainty is simply the absolute uncertainty expressed as a fraction (or percentage) of the measured value, so the two forms always convert directly into each other. This tool is intended for general science and engineering education, not as a substitute for a formal measurement-uncertainty analysis in a lab or industrial setting.