About the Significant Figures Calculator
What is the Significant Figures Calculator?
Significant figures show how precisely a quantity is known. This calculator counts them using the standard rules and rounds your number to the precision you choose.
It accepts decimals and scientific notation such as 1.20e3.
How to use the Significant Figures Calculator
- Number (sample: 0.004560)
- Round to How Many Significant Figures (sample: 2)
- Press Count & Round Significant Figures (results also refresh as you type). The result card shows the Significant Figures, along with Rounded to 2 significant figures, Scientific notation, Decimal places in the number and Note.
Formula used
Count all digits except leading zeros; trailing zeros count only with a decimal point
- Examples = 0.004560 → 4; 1200 → 2 (ambiguous); 1200. → 4; 1.20 × 10³ → 3
Write numbers in scientific notation to make trailing zeros unambiguous.
Worked example
These are the sample values already filled in the calculator above, and the result it returns for them:
| Input | Sample value |
|---|---|
| Number | 0.004560 |
| Round to How Many Significant Figures | 2 |
| Result | Value |
|---|---|
| Significant Figures | 4 |
| Rounded to 2 significant figures | 0.0046 |
| Scientific notation | 4.6 × 10^-3 |
| Decimal places in the number | 6 |
| Note | Leading zeros are never significant; trailing zeros after a decimal point are |
Tips for using the Significant Figures Calculator
- In multiplication and division, round the answer to the fewest significant figures among the inputs.
- In addition and subtraction, round to the fewest decimal places.