Significant Figures Calculator
Calculate significant figures, round numbers, and perform arithmetic operations while maintaining proper precision.
Round to significant figures: (optional)
1Rules for Significant Figures
Determining the number of significant figures (sig figs) in a number is crucial for scientific accuracy. Follow these standard rules:
- Non-zero digits are always significant. (e.g., 22 has 2 sig figs, 22.3 has 3).
- Zeros between non-zero digits are significant. (e.g., 101 has 3 sig figs).
- Leading zeros are never significant. They only indicate the position of the decimal point. (e.g., 0.005 has 1 sig fig).
- Trailing zeros in a decimal number are significant. (e.g., 2.30 has 3 sig figs).
- Trailing zeros in a whole number without a decimal point are not significant unless specified (often using an overbar). (e.g., 1000 usually has 1 sig fig).
2Arithmetic Operations
Addition and Subtraction
When adding or subtracting, the result should have the same number of decimal places as the number with the fewest decimal places in the calculation.
+ 5.2
-------
17.31 → 17.3 (1 decimal place)
Multiplication and Division
When multiplying or dividing, the result should have the same number of significant figures as the number with the fewest significant figures in the calculation.
x 3.42 (3 sig figs)
-------
8.55 → 8.6 (2 sig figs)
?Frequently Asked Questions
Why are significant figures important?
They show the precision of a measurement. When you perform calculations with measurements, the result cannot be more precise than the least precise measurement used.
How do I handle exact numbers?
Exact numbers (like counting items, e.g., 3 apples) have an infinite number of significant figures and do not limit the precision of the result.
What about scientific notation?
Scientific notation is often used to clearly express the number of significant figures. All digits in the coefficient of a number written in scientific notation are significant (e.g., 2.00 x 10³ has 3 sig figs).