Significant Figures Calculator
Solve expressions and round results to any number of significant figures.
Round to significant figures: (optional)
Count and Calculate With Significant Figures
Enter any number to count its significant figures instantly — or run addition, subtraction, multiplication, and division with results rounded to the correct number of sig figs automatically.
The on-screen keypad makes entry fast on phones and tablets, and every result shows which sig-fig rule was applied, so it doubles as a study aid.
Count and arithmetic
Count sig figs in any number, then add, subtract, multiply, or divide with automatic correct rounding.
On-screen keypad
Tap digits, decimal points, and operators on the built-in keypad — handy on touchscreens and during homework.
Free and private
All math runs locally in your browser — no signup, no uploads, and instant answers for every entry.
How to use
- Type a number (or tap it in on the keypad).
- See the sig-fig count, or pick an operation for sig-fig arithmetic.
- Read the correctly rounded result and the rule applied.
Frequently Asked Questions
What are significant figures?
Significant figures are the digits in a number that carry meaning about its precision — all non-zero digits, zeros between them, and trailing zeros after a decimal point.
How do sig figs work in multiplication?
The result is rounded to the same number of significant figures as the input with the fewest sig figs.
How do sig figs work in addition?
The result is rounded to the same decimal place as the least precise input (the one with the fewest decimal places).
Are zeros always significant?
No. Leading zeros are never significant; zeros between non-zero digits are; trailing zeros count only if there is a decimal point.
Is the calculator free?
Yes, free with no signup.
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