Significant figures express how precisely a quantity is known. Leading zeros are never significant.
How to use the Significant Figures Calculator
- Number
- Significant figures
Results update as you type, and every field accepts the units shown in its menu.
How it works
Find the position of the first non-zero digit using log₁₀, then round to the requested number of digits from there.
Inputs explained
| Field | What to enter |
|---|---|
| Number | A number |
| Significant figures | A number |
What each result means
- Rounded = round([Number], [Significant figures] – 1 – [Magnitude])
- Scientific coefficient = round([Number] ÷ 10^[Magnitude], [Significant figures] – 1)
- Power of ten = [Magnitude]
Example values
How the main result changes when Number changes and everything else stays at the example values above:
| Number | Rounded |
|---|---|
| 0.0023 | 0.0023 |
| 0.0034 | 0.0034 |
| 0.0046 | 0.0046 |
| 0.0057 | 0.0057 |
| 0.0069 | 0.0069 |
| 0.0091 | 0.0091 |
Formula
Rounded = round(x, s − 1 − floor(log₁₀|x|))Worked example
Inputs — Number: 0.00456789; Significant figures: 3.
Results — Rounded = 0.00457; Scientific coefficient = 4.57; Power of ten = -3.
Frequently asked questions
Are trailing zeros significant?
After a decimal point, yes: 2.50 has three significant figures.
How many significant figures in 1200?
Ambiguous; write 1.2 × 10³ or 1.200 × 10³ to be clear.
What formula does the Significant Figures Calculator use?
Rounded = round(x, s − 1 − floor(log₁₀|x|)).