Significant Figures Calculator
Solve expressions and round results to any number of significant figures.
Round to significant figures: (optional)
Invalid expression.
1
Expression:
2
Exact result:
Answer:
—
Significant Figures: —
Decimals: —
Scientific Notation:
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What are Significant Figures?
Significant figures (sig figs) are the meaningful digits in a number — the ones that carry real precision. Understanding them is essential in science, engineering, and any field where measurement accuracy matters.
How to Count Significant Figures
These ARE significant
- • Any non-zero digit (e.g.
7in673) - • Zeros between non-zero digits (e.g.
0in205) - • Trailing zeros after a decimal point (e.g.
90.7500has 6 sig figs)
These are NOT significant
- • Leading zeros (e.g.
007has 1 sig fig) - • Leading zeros after a decimal (e.g.
0.007has 1 sig fig) - • Trailing zeros without a decimal point (e.g.
100has 1 sig fig)
Examples
| Number | Sig Figs | Explanation |
|---|---|---|
| 7 | 1 | Single non-zero digit |
| 100 | 1 | Trailing zeros, no decimal |
| 0.0637 | 3 | Leading zeros are not significant |
| 30.00 | 4 | Trailing zeros after decimal ARE significant |
| 673.52 | 5 | All non-zero digits are significant |
| 0.0025 | 2 | Only 2 and 5 are significant |
Supported Operators
+ - * /
Arithmetic
^
Exponent
( )
Grouping
log( )
Base-10 log
ln( )
Natural log
Frequently Asked Questions
Significant figures are the digits in a number that contribute to its precision. They include all non-zero digits, zeros between non-zero digits, and trailing zeros after a decimal point. Leading zeros are never significant.
Enter any mathematical expression (e.g.
1.5 / log(6)), choose how many significant figures to round to, and click Calculate. The tool evaluates the expression, then rounds the result to your chosen precision while showing the exact value and sig fig count.
Most scientific and educational contexts use standard rounding (round half up), not banker's rounding. This calculator follows the standard rule for simplicity and consistency — just like most textbooks.
For addition and subtraction, the result should be rounded to the least number of decimal places in the inputs — not sig figs. For example, 12.11 + 18.0 = 30.1 (1 decimal place), not 30.11.
Scientific notation expresses a number as a coefficient between 1 and 10 multiplied by a power of 10 (e.g. 1.5 × 10²). It's especially useful for very large or very small numbers and makes sig figs immediately obvious.
It means you keep only the 3 most meaningful digits. For example, 1,234,567 rounded to 3 sig figs is 1,230,000 (or 1.23 × 10⁶). The value 0.009876 rounded to 3 sig figs is 0.00988.
Yes! This calculator is ideal for chemistry, physics, and other sciences where measurement precision is critical. It supports expressions involving logarithms (log and ln), which are commonly used in pH, equilibrium, and thermodynamics calculations.
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