Significant Figures Calculator
Round any number to your chosen count of significant figures.
Calculator
Use the Significant Figures Calculator
Result
—
Formula
round to n significant digits
Step-by-step
- 1
Enter the number
The value to round.
- 2
Choose the precision
How many significant figures to keep.
Worked example
Example input: n: 3.14159, figs: 3
Result: 3.14
Related tools
- Scientific Notation
Compact large/small numbers.
- Common Log
Log base 10 of any number.
Frequently asked questions
How many significant figures does 0.70 have?
Two. Leading zeros are never significant, so in 0.70 the significant digits are the 7 and the trailing 0 — zeros after a decimal point do count.
Do trailing zeros count as significant?
After a decimal point, yes: 1.20 has three significant figures. In a whole number written without a decimal point, such as 120, trailing zeros are usually not significant, so 120 has two.
What is the rounding rule at the boundary?
If the first digit you drop is 5 or greater, round the last kept digit up; otherwise keep it unchanged. For example, 3.14159 rounded to 3 significant figures is 3.14.
Why does rounding change the number of digits shown?
The calculator rounds to a place value (for example, thousandths for 3 figures of a number like 3.14159), so trailing zeros are not added to the display. The rounded value is mathematically correct even if it shows fewer digits.
How many significant figures does 3.14159 have?
Six — every digit from the first nonzero digit to the last is significant: 3, 1, 4, 1, 5, 9. Rounded to 3 significant figures it becomes 3.14; to 2 it becomes 3.1.
What is 55580.5 to 2 significant figures?
56000. Keep the first two figures (55), then look at the next digit — a 5 rounds the second figure up — giving 5.6 × 10⁴, which is 56,000 in plain digits.