How it works
Round the decimal value to the requested significant figures using half-up rounding. Trailing zeros are retained when needed to show the chosen precision.
Input definitions
- Number (decimal or scientific notation)
- Enter the value in the labeled unit.
- Significant figures (1–30)
- Enter the value in the labeled unit.
A worked example
- Number (decimal or scientific notation)
- 0.00123456
- Significant figures (1–30)
- 3
Assumptions & limits
Explicit half-up rounding; scientific notation is used for sufficiently large or small values. Does not infer precision from a measurement or apply uncertainty propagation. Zero is displayed at the requested precision.
Sources & review
Maintained by AnsRio. Methods and examples use automated checks; this does not imply independent professional certification.
Method updated 2026-10-18. Content checked against the stated method and examples. Our verification approach.
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Common questions
How are halfway values rounded?
This tool uses half-up rounding: 1.25 to two significant figures is 1.3, and −1.25 becomes −1.3. It does not use ties-to-even rounding.
Are significant figures the same as decimal places?
No. Significant figures begin with the first nonzero digit. For example, 0.00123456 rounded to three significant figures is 0.00123; three decimal places would give 0.001.
Why does the answer include trailing zeros?
Trailing zeros in a displayed result can identify the requested precision. For example, 12 rounded to four significant figures is 12.00. This display does not establish the accuracy of the original measurement.