Significant figures calculator
Round a number to a chosen number of significant figures.
How do I use this page?
- Enter values or use the example in the form.
- Choose a mode or units where available.
- Read the result and check the calculation steps below.
What this page does not do: You choose output precision, not measurement accuracy. Calculations use floating-point arithmetic; boundary values may require checking.
Further reading
Theory — what are significant figures?
Significant figures are the digits of a number that carry information about its precision. The calculator rounds an entered number to a chosen number of significant figures — for example, 12345 rounded to three significant figures becomes 1.23 times ten to the fourth power. Leading zeros are not significant, so 0.004567 rounded to three significant figures becomes 0.00457. Keeping trailing zeros in the result shows which precision was chosen.
Frequently asked questions
How is the result calculated?
What are the limitations?
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