Significant Figures Calculator
Free online significant figures calculator. Count and round to significant figures with rules for zeros and decimals.
About This Free Online Significant Figures Calculator
Our free online significant figures calculator counts the number of significant figures in any number and can round values to a specified number of significant digits. It follows all standard sig fig rules: non-zero digits are always significant, captive zeros are significant, leading zeros are not, trailing zeros are significant only if there is a decimal point. Perfect for chemistry, physics, and engineering students.
Features of Our Significant Figures Calculator
- Count significant figures in any number
- Round to specified number of sig figs
- Scientific notation support
- Shows which digits are significant
- Reference rules panel with examples
- 100% private — browser-only processing
How to Use the Significant Figures Calculator
The Significant Figures Calculator works right in your browser — no signup, no installation. Follow these steps:
- Enter a number with any decimal places and zeros.
- The calculator instantly shows the sig fig count and highlights significant digits.
- Optionally set a target sig fig count to round the number.
- View the result and the rule explanation.
Frequently Asked Questions About Significant Figures Calculator
What are the rules for significant figures?
1) All non-zero digits are significant. 2) Zeros between non-zero digits are significant. 3) Leading zeros are not significant. 4) Trailing zeros after decimal are significant. 5) Trailing zeros without decimal are ambiguous.
How many sig figs in 100?
100 has 1 significant figure (the 1). The zeros are ambiguous — they could be placeholders or measurements. Writing 100. (with decimal) makes it 3 sig figs. Scientific notation (1.00 × 10²) makes it 3.
Why are significant figures important?
Significant figures indicate the precision of a measurement. They prevent you from claiming more precision than your instruments actually provide. In science and engineering, using correct sig figs is essential for accurate calculations.
Why Choose the Significant Figures Calculator?
The Significant Figures Calculator is built for answers you can rely on, not rough guesses. Every calculation happens locally in your browser the moment you enter a value, so results are immediate, the math is transparent, and nothing you type ever leaves your device.