Significant Figures Calculator
Instantly round any number to your desired number of significant digits and convert it to scientific notation with ease.
Round to Significant Figures
Enter your number and the desired amount of significant figures to instantly see the correctly rounded result and its scientific notation equivalent.
Sig Fig Converter
Get precise rounding for your scientific and mathematical calculations.
How it Works
Understanding significant figure rounding
Identify First Sig Fig
We locate the first non-zero digit in your number, which marks the beginning of the significant figures.
Count to Target
We count exactly the number of significant digits you requested, starting from that first non-zero digit.
Apply Rounding Rules
We look at the next digit. If it’s 5 or greater, we round up the last significant digit. If it’s less than 5, we leave it as is.
Format Output
We present the result in standard decimal format (preserving necessary trailing zeros) and scientific notation for clarity.
Rules for Significant Figures
A quick reference guide for determining which digits in a number are considered significant in scientific and mathematical contexts.
| Rule | Description | Example |
|---|---|---|
| Non-zero digits | All non-zero digits are always significant. | 456 has 3 sig figs |
| Sandwiched zeros | Zeros between non-zero digits are significant. | 4006 has 4 sig figs |
| Leading zeros | Zeros to the left of the first non-zero digit are never significant. | 0.0045 has 2 sig figs |
| Trailing zeros (with decimal) | Zeros at the end of a number are significant only if there is a decimal point. | 4.500 has 4 sig figs |
| Trailing zeros (no decimal) | Zeros at the end of a whole number are ambiguous, but usually not significant. | 4500 has 2 sig figs (typically) |
Significant Figures FAQ
Answers to the most frequently asked questions about rounding, precision, and significant digits in mathematics.
Significant figures (or sig figs) are the digits in a number that carry meaning contributing to its measurement resolution. This includes all non-zero digits, any zeros between significant digits, and trailing zeros in a decimal number.
1. All non-zero digits are significant. 2. Zeros between non-zero digits are significant. 3. Leading zeros are never significant. 4. Trailing zeros are only significant if the number contains a decimal point.
Identify the first significant digit, count to the desired number of significant figures, and look at the next digit. If it is 5 or greater, round up the last significant digit. If it is less than 5, leave the last significant digit as is.
No, scientific notation is actually the best way to clearly indicate significant figures. For example, 1.20 × 10³ clearly has three significant figures, whereas 1200 is ambiguous.