What is Significant Figures?
The Significant Figures Calculator counts the number of significant figures (sig figs) in a number and rounds to a specified number of significant figures. This is crucial in science and engineering where measurement precision matters.
Significant figures indicate the precision of a measurement. A lab balance reading 12.34 g has 4 sig figs, meaning the measurement is precise to the hundredths place. When doing calculations, the result should not have more sig figs than the least precise input.
Rules for counting sig figs: 1. All non-zero digits are significant (123 = 3 sig figs) 2. Zeros between non-zero digits are significant (105 = 3 sig figs) 3. Leading zeros are NOT significant (0.0045 = 2 sig figs) 4. Trailing zeros after a decimal point ARE significant (12.50 = 4 sig figs) 5. Trailing zeros in a whole number are ambiguous (1500 = 2-4 sig figs, use scientific notation to clarify)
Formula
Sig Fig Rules: - 123 → 3 sig figs - 0.0045 → 2 sig figs (leading zeros don't count) - 100.0 → 4 sig figs (trailing zero after decimal counts) - 1500 → ambiguous (2, 3, or 4) - 1.500 × 10³ → 4 sig figs (unambiguous)
Rounding to sig figs: 123456 to 3 sig figs = 123000 0.004567 to 2 sig figs = 0.0046 78.945 to 4 sig figs = 78.95
How to use this Significant Figures Calculator?
1. Enter any number. 2. Enter how many sig figs to round to. 3. See the sig fig count, rounded result, and scientific notation.