Significant Figures Calculator

Free online tool to calculate significant figures with step-by-step rules and examples. Perfect for students, scientists, and engineers.

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Results

What are Significant Figures?


Significant figures (sig figs for short) are the meaningful digits in a number. Often, leading zeroes or trailing zeroes can be removed and the number remains just as accurate (004 means the same as 4, for example).

When removing digits, you must be able to identify the significant figures in order to retain the number's accuracy. When you round a number up or down, one or some of the significant figures are altered.

  • • Solves expressions and counts the number of significant figures.
  • • Does not apply the even rule.
  • • Addition and subtraction round by least number of decimals.
  • • Supports advanced mathematical functions: trigonometry, logarithms, factorials, combinations, and permutations.

How to Use

Supported Functions:

  • • Basic: +, -, ×, ÷, ^, ( )
  • • Advanced: sin, cos, tan, log, ln, sqrt
  • • Special: factorial (!), absolute (abs), π, e
  • • Combinatorics: nCr, nPr, percentage (%)
  • • Memory: MC, MR, M+, M-

Keyboard Shortcuts:

  • • Enter: Calculate result
  • • Escape: Clear expression
  • • Ctrl/Cmd + T: Cycle themes
  • • Click history items to reuse
  • • Numbers and operators work directly

Significant Figures Examples

7

1 significant figure

7 has 1 significant figure (7).

73

2 significant figures

73 has 2 significant figures (7 and 3).

100

1 significant figure

100 has 1 significant figure (1) since there's no decimal point.

673

3 significant figures

673 has 3 significant figures (6, 7, and 3).

673.52

5 significant figures

673.52 has 5 significant figures (6, 7, 3, 5, and 2).

0.0637

3 significant figures

0.0637 has 3 significant figures (6, 3, and 7). Leading zeroes are not significant.

30.00

4 significant figures

30.00 has 4 significant figures (3, 0, 0 and 0) with 2 decimal places.

0.0025

2 significant figures

0.0025 has 2 significant figures (2 and 5) with 4 decimal places.

Rules for Significant Figures

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Counting Significant Figures

1. All non-zero digits are significant
123 has 3 significant figures
4.56 has 3 significant figures
2. Leading zeros are NOT significant (they just locate the decimal point)
0.052 has 2 significant figures
0.004 has 1 significant figure
3. Zeros between non-zero digits are significant
105 has 3 significant figures
2.03 has 3 significant figures
4. Trailing zeros in a decimal number are significant
2.30 has 3 significant figures
0.500 has 3 significant figures
5. Trailing zeros in a whole number may or may not be significant (use scientific notation to clarify)
1500 could be 2, 3, or 4 significant figures
1.50 × 10² clearly has 3 significant figures

Arithmetic Operations

1. Addition and Subtraction: Round to the least number of decimal places
12.1 + 0.35 = 12.45 → 12.5 (1 decimal place)
100.0 - 0.23 = 99.77 → 99.8 (1 decimal place)
2. Multiplication and Division: Round to the least number of significant figures
2.1 × 3.456 = 7.2576 → 7.3 (2 sig figs)
8.314 ÷ 2.5 = 3.3256 → 3.3 (2 sig figs)
3. Powers and Roots: The result has the same number of significant figures as the original number
(2.4)² = 5.76 → 5.8 (2 sig figs)
√(16) = 4.0 → 4.0 (2 sig figs if 16 has 2 sig figs)
4. Logarithms: The number of digits after the decimal point equals the number of significant figures in the original number
log(2.4) = 0.38 → 0.38 (2 decimal places)

Scientific Notation

1. Scientific notation clearly shows the number of significant figures
1.23 × 10³ has 3 significant figures (represents 1230)
5.0 × 10⁻⁴ has 2 significant figures (represents 0.00050)
2. The exponent does not affect the number of significant figures
2.5 × 10⁶ and 2.5 × 10⁻⁶ both have 2 significant figures