Experimental data & uncertainty · SL/HL
Percentage Uncertainty Calculator
Enter a non-zero measured value and a non-negative absolute uncertainty in the same unit.
Your values
Start with the example or enter your own values. Use a dot for decimals and e for scientific notation.
Calculated locally. No account or input upload.
Result & working
ExampleThe calculator is loading. The worked example is also shown below.
Step-by-step working
The formula
percentage uncertainty = Δx/|x| × 100%
| Symbol | Meaning |
|---|---|
| Δx | Absolute uncertainty in the same unit as x. |
When to use this calculator
Percentage uncertainty lets you compare the relative size of uncertainty across measurements.
Worked example
The page opens with these example values. The result below is pre-generated for reference.
- Percentage uncertainty = Δx/|x| × 100
- = 0.05 / |25| × 100 = 0.2%
- Rounded measurement: (25.00 ± 0.05) cm³
(25.00 ± 0.05) cm³
Common mistakes
- Convert value and uncertainty to the same unit first.