Math

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Significant Figures Calculator.

Round a number to an explicit significant-figure count.

On-device calculationNo signup
01

Set your values

Results update as you type.

Rounded value: 123.5

Rounded value

0.000000
Significant figures: 4

Significant figures

0.000000

Results update automatically as you type.

Use Cases

Rounding measurements in science labs

When recording experimental data, you often need to round results to a certain number of significant figures to reflect the precision of your instruments.

Example: Round 9.8765 m to 3 significant figures → 9.88 m

Simplifying engineering calculations

Engineers frequently round intermediate and final values to a consistent number of significant figures to avoid false precision and simplify calculations.

Example: Round 1234.56 N to 2 significant figures → 1200 N

Frequently Asked Questions

What are significant figures?
Significant figures are the digits in a number that carry meaning and contribute to its precision. They include all non-zero digits, zeros between non-zero digits, and trailing zeros in the decimal part. Leading zeros are not significant.
How do I use this calculator?
Enter the number you want to round in the 'Value' field, and specify the desired number of significant figures in the 'Significant figures' field. The calculator will round the number to that many significant figures and display the result.
Can this calculator handle very large or very small numbers?
Yes, the calculator can handle numbers in standard decimal notation, including very large and very small values. It will round them to the specified number of significant figures, which is useful in scientific contexts.

Tips & Common Mistakes

Tips

  • Remember that leading zeros are not significant. For example, 0.0034 has only two significant figures.
  • When rounding, if the digit after the last significant figure is 5 or greater, round up; otherwise, leave it as is.
  • Use the calculator to check your manual rounding, especially with numbers that have many digits or trailing zeros.
  • For numbers in scientific notation, the exponent does not affect the number of significant figures.

Common Mistakes to Avoid

  • Counting leading zeros as significant. For instance, 0.0025 has only two significant figures, not four.
  • Forgetting that trailing zeros in a decimal number are significant. For example, 2.50 has three significant figures.
  • Rounding to a number of decimal places instead of significant figures. This calculator specifically rounds to significant figures, not decimal places.

Last updated: August 13, 2026