Significant figures calculator
Round inputs and show significant-digit conventions.
How to use Significant figures calculator
The Significant figures calculator rounds a number to 1 to 15 significant digits and also counts the significant digits in the number as you typed it. Sign, decimal point and leading zeros are not counted, and trailing decimal zeros are treated as significant. The default example rounds 0.012345 to three significant digits, giving 0.0123.
- Enter the requested values in the settings panel.
- Set number (preserve entered digits), significant digits.
- Run significant figures calculator, review the output, then use the available copy or download controls.
What this tool supports
Round inputs and show significant-digit conventions.
- Number (preserve entered digits)
- Set this value for your task.
- Significant digits
- Range: 1 to 15
Limits and processing
Local bounded calculations. Numeric inputs must be finite and within the visible ranges. Lists and tables have operation-specific limits. Models, estimates and supplied rates must be checked against your intended use.
Frequently asked questions
How do I round a number to 3 significant figures?
Enter the number and set Significant digits to 3. For example, 0.012345 becomes 0.0123 and 123456 becomes 1.23e+5, since rounding large integers can switch the output to exponent form.
How many significant figures does 0.00450 have?
Three. Leading zeros only show the position of the decimal point, so they are not counted, while the trailing zero after the 5 in a decimal is significant. The calculator reports this as Entered significant digits.
Are trailing zeros in a whole number significant?
They are ambiguous. In 1200 it is unclear whether the zeros were measured. The calculator counts every digit after leading zeros, so it reports 4, and notes that integer trailing zeros are ambiguous. Use scientific notation such as 1.2e3 to be explicit.
Where is my input processed?
This operation processes its source in your browser. Copy and download are explicit actions; source input is not saved in an account or history.
What are the input limits?
Local bounded calculations. Numeric inputs must be finite and within the visible ranges. Lists and tables have operation-specific limits. Models, estimates and supplied rates must be checked against your intended use.