Significant Figures Calculator
Round numbers to significant figures and count sig figs
Calculator
• 3 non-zero digit(s) are significant
• 1 trailing zero(s) after decimal are significant
Significant Figures Rules
- 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 point ARE significant
- 5. Trailing zeros in whole numbers may or may not be significant
How to Use
Count and round significant figures in numbers
Enter number
Input a number to analyze or round
Choose mode
Select to count sig figs or round to specific sig figs
View analysis
See which digits are significant and the rounded result
Significant Figures Rules
Count: non-zero digits, zeros between, trailing after decimal
Rules determine which digits carry meaningful precision.
Frequently Asked Questions
Significant figures (sig figs) are the digits in a number that carry meaningful precision. They indicate measurement accuracy. 2.50 has 3 sig figs (the zero shows precision to hundredths), while 250 might have 2 or 3 sig figs depending on context.
All non-zero digits are significant. Zeros between non-zeros are significant. Leading zeros are not significant (0.005 = 1 sig fig). Trailing zeros after decimal are significant (2.50 = 3 sig figs). Trailing zeros without decimal may or may not be significant.
Count that many significant digits from the left-most non-zero digit, then round the last kept digit based on what follows. 3.14159 to 3 sig figs = 3.14. 0.004567 to 2 sig figs = 0.0046. 12,345 to 2 sig figs = 12,000.
For multiplication/division: result has the same sig figs as the input with fewest sig figs. For addition/subtraction: result has the same decimal places as the input with fewest decimal places. This preserves measurement precision.