Significant Figures Calculator - Sig Figs
Calculate the number of significant figures in any number and perform mathematical operations while preserving precision. Essential for scientific and engineering calculations where measurement accuracy matters. Supports addition, subtraction, multiplication, and division with proper sig fig rules.
Significant Figures Rules
Result = same as the least number of significant figures in the operandsVariables:
- Non-zeroAll non-zero digits are significantAll non-zero digits are significant(e.g.: 123 = 3 SF)
- Captive zerosZeros between significant digits are significantZeros between significant digits are significant(e.g.: 101 = 3 SF)
- Leading zerosLeading zeros are not significantLeading zeros are not significant(e.g.: 0.05 = 1 SF)
- Trailing zerosSignificant if there is a decimal pointSignificant if there is a decimal point(e.g.: 50.0 = 3 SF)
How to Determine Significant Figures
- 1
Identify Non-Zero Digits
All digits 1–9 are always significant.
- 2
Check Zeros in the Middle
Zeros sandwiched between significant digits are significant.
- 3
Ignore Leading Zeros
Zeros before the first non-zero digit are not significant (0.005 = 1 sig fig).
- 4
Trailing Zeros Depend on Context
Trailing zeros are significant if there is a decimal point (50.0 = 3 sig figs; 50 alone is ambiguous).
Examples
Counting Significant Figures
How many significant figures are in 0.00340?
- 1.Leading 0.00 = not significant
- 2.3 = significant (1st)
- 3.4 = significant (2nd)
- 4.Trailing 0 with decimal = significant (3rd)
0.00340 has 3 significant figures: 3, 4, and the final 0.
Multiplication with Significant Figures
Calculate 2.5 × 3.42 using sig fig rules
- 1.2.5 has 2 sig figs
- 2.3.42 has 3 sig figs
- 3.Raw result = 8.55
- 4.Round to 2 sig figs (fewest)
The result rounds to 2 significant figures because 2.5 only has 2.
Addition with Significant Figures
Calculate 12.11 + 0.3 using sig fig rules
- 1.12.11 = 2 decimal places
- 2.0.3 = 1 decimal place
- 3.Raw result = 12.41
- 4.Round to 1 decimal place
For addition/subtraction, the result follows the fewest decimal places.