School calculator
Significant Figures Calculator
Count sig figs, round, and get scientific notation.
Quick answer
How do you count significant figures?
Count every non-zero digit, every zero between non-zero digits, and trailing zeros only if the number has a decimal point. Leading zeros never count. So 0.004560 has 4 sig figs, 1200 has 2, and 1200. has 4.
Non-zero digits are significant. Zeros between non-zero digits are significant. Leading zeros are not. Trailing zeros count only when there is a decimal point.
⚡ Answer updates as you type · Enter = calculate · Esc = reset
- Non-zero digits (3) are always significant.
- Leading zeros (3) are not significant.
- Trailing zeros after a decimal point are significant.
- Total: 4 significant figures.
Count significant figures in any number, see which rule applies to each zero, and round to a chosen number of sig figs with scientific notation.
About this Significant Figures Calculator
The Significant Figures Calculator counts the sig figs in any number and explains which rule applies to each digit — leading zeros, trapped zeros, and trailing zeros. It also rounds to any number of significant figures and writes the answer in scientific notation, just like chemistry and physics classes require.
What you'll need
- • Number, written normally or in e-notation (6.02e23)
- • Number of significant figures to round to
How it works
- 1. Type the number exactly as written (trailing zeros matter).
- 2. The calculator skips leading zeros.
- 3. It counts non-zero digits and zeros trapped between them.
- 4. It counts trailing zeros only when there is a decimal point.
- 5. Choose a sig fig count to round and see scientific notation.
Worked example
0.004560 → leading zeros don't count, 4, 5, 6 count, and the trailing 0 after the decimal counts = 4 sig figs (4.560 × 10^-3). Rounded to 2 sig figs it is 0.0046.
Related searches
Significant Figures Calculator FAQ
What is the Significant Figures Calculator?
The Significant Figures Calculator is a free online tool that helps you count sig figs, round, and get scientific notation.
How do I use the Significant Figures Calculator?
Open the Significant Figures Calculator, enter the requested values, and review the instant estimate on the page.
Is the Significant Figures Calculator free?
Yes. The Significant Figures Calculator is free to use on Fast Online Calculator and does not require an account.
How many significant figures are in 100?
100 has 1 significant figure, because trailing zeros without a decimal point are not significant. Written as 100. or 1.00 × 10^2 it has 3.
Are zeros significant?
It depends on position: zeros between non-zero digits (1002) are significant, leading zeros (0.05) are not, and trailing zeros count only with a decimal point (3.0 has 2).
How do you round to significant figures?
Start at the first non-zero digit, count the number of sig figs you need, and round the last kept digit using the next digit. 12,345 to 3 sig figs is 12,300.
How do sig figs work in multiplication and division?
Round the answer to the smallest number of significant figures among the numbers you multiplied or divided. 2.5 × 3.42 = 8.55, rounded to 2 sig figs = 8.6.
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