Sig Fig Calculator
Count significant figures and round to any number of sig figs with this free online sig fig calculator, with decimal, scientific and E-notation results.
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Part of the toolkit
How to use Sig Fig Calculator
- 1Type a number — decimals, whole numbers and scientific notation like 6.022e23 or 6.022×10^23 all work
- 2See how many significant figures it has, with the significant digits underlined
- 3Enter how many sig figs to round to and copy the decimal, scientific or E-notation result
Frequently asked questions
How many significant figures does 0.00450 have?▾
Three: 4, 5 and the trailing 0. Leading zeros only place the decimal point, but a trailing zero after the decimal point is measured and counts.
Are trailing zeros significant?▾
After a decimal point, yes (2.50 has 3). In a whole number with no decimal point they're ambiguous — 4500 is usually counted as 2 — so write 4500. or 4.500 × 10³ if all four digits are measured.
How do I round to 3 significant figures?▾
Keep the first three significant digits and look at the next one: 5 or more rounds up. 0.0012345 → 0.00123, and 9.996 → 10.0 (the carry adds a digit, so the zero after the point keeps 3 sig figs).
Why use this instead of a regular calculator?▾
Rounding happens on the exact decimal digits you typed, so results like 1.05 → 1.1 are correct — ordinary floating-point math can round these the wrong way.
Embed Sig Fig Calculator on your website▾
Paste this snippet into your page. The embedded tool runs in your visitor's browser and shows a small “Powered by clkr.work” link.