Absolute Uncertainty Calculator
Enter a measured value and its absolute uncertainty to view the measurement interval and formatted result.
Reported measurement
12.5000 ± 0.3000
Interval: [12.2000, 12.8000]
How to Use This Calculator
- Enter the measured or central value.
- Specify the absolute uncertainty (half-width of the confidence interval).
- Review the formatted result with ± notation and the implied lower/upper bounds.
- Report measurements with uncertainty to communicate possible variation clearly.
Formula
Reported value = x ± Δx
Lower bound = x − Δx
Upper bound = x + Δx
Here x is the measured value and Δx is the absolute uncertainty assumed to be symmetric around x.
Full Description
Absolute uncertainty expresses the possible deviation of a measured value in the same units as the measurement. Reporting x ± Δx conveys both the central value and its range, reflecting instrument precision or experimental repeatability.
Absolute uncertainties combine with other measurements through propagation rules to estimate error in derived quantities.
Frequently Asked Questions
How is absolute uncertainty different from relative uncertainty?
Absolute uncertainty uses the same units as the measurement; relative uncertainty scales the error as a percentage of the value.
What if I only know relative error?
Multiply the relative error by the measured value to convert it to absolute uncertainty.
Can uncertainty be zero?
In practice, no measurement is exact. If Δx = 0, it indicates unspecified or negligible uncertainty.
What about asymmetric uncertainties?
This tool assumes symmetric uncertainty. For asymmetric intervals, report separate ± values or use interval notation.