Experimental data & uncertainty · SL/HL
Significant Figures Calculator
Enter the value exactly as written and choose 1–15 significant figures.
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
Keep the requested number of significant digits; use the first discarded digit to round.
| Symbol | Meaning |
|---|---|
| significant digit | A digit conveying the precision represented by the written number. |
When to use this calculator
Course calculations should preserve guard digits internally and round final reported quantities appropriately.
Worked example
The page opens with these example values. The result below is pre-generated for reference.
- Input: 0.004560
- Requested significant figures: 3
- Rounded: 4.56 × 10^-3
- The written input indicates 4 significant figures. Leading zeros are not significant; zeros between significant digits are significant. Trailing zeros in a decimal or scientific-notation mantissa express precision. The first discarded digit determines rounding. Exact halfway cases round away from zero. Adding zeros cannot improve measurement precision.
4.56 × 10^-3
Common mistakes
- Leading zeros are placeholders.
- Trailing zeros in a decimal can communicate precision.