How many significant figures does 0.004560 have?

It has four: 4, 5, 6 and the trailing 0 after the decimal point. The leading zeros only locate the decimal point. Type the number exactly as written, because trailing zeros change the count.

How do I round a number to 3 significant figures and keep trailing zeros?

Enter the Number, then set the Round to (sig figs) slider to 3. The result keeps trailing zeros, so 2.5 rounded to 3 sig figs shows 2.50. Use Copy to take the formatted value.

Do trailing zeros in a whole number like 1200 count as significant?

Not when there is no decimal point, so 1200 has two significant figures. Writing 1200. or 1.200e3 makes the zeros count. The tool labels each digit as significant, leading zero or trailing zero.

Can I enter scientific notation or numbers with commas?

Yes. It accepts forms like 4.56e3 and thousands separators such as 1,234,567.8, and a single comma like 1,5 is read as a decimal point. Only the mantissa digits count in scientific notation.

How many sig figs can I round to, and can I get scientific or engineering notation?

The slider rounds to 1 to 10 sig figs, and a table lists 1 to 6. Choose Decimal, Scientific or Engineering notation to change how the rounded result is displayed.

Yes. Every tool is free to use, with no account and no credit card. The work runs on your device rather than on our servers, which is what keeps it free to run.

Does it work on mobile?

Yes. It runs in current mobile browsers on iOS and Android, with nothing to install.

🔬

Free Significant Figures Calculator

Count the significant figures in a number and round it to any number of sig figs.

Runs in your browserNo sign-up, no pop-upsNo login requiredFree foreverCounts + roundsRules explained

Works offline once loaded

Count how many significant figures a number has and round it to a chosen number of sig figs, with trailing zeros preserved. Calculated in your browser.

Number

Round to (sig figs): 3

Sig figs in input

Rounded to 3 sig figs

0.00456

Numeric value: 0.00456

Digit by digit

0.004560

SignificantLeading zero — not significant

Leading zeros only locate the decimal point — they are never significant.

Rounded to 1-6 sig figs

10.005

20.0046

30.00456

40.004560

50.0045600

60.00456000

Rules: non-zero digits are always significant; zeros between them are significant; leading zeros are not; trailing zeros count only when there is a decimal point.

🔒 Everything is calculated in your browser — nothing is uploaded.

Common uses

Count Sig FigsHow many significant figures does a number have?
Round to Sig FigsRound any number to N significant figures.
Chemistry Sig FigsGet measurement precision right in chemistry.
Physics RoundingRound physics answers properly.
Lab Report PrecisionReport lab values with correct precision.
Leading Zeros RuleWhy 0.0042 has two sig figs.

How It Works

Count how many significant figures a number has — applying the standard rules for leading, captive and trailing zeros — and round any number to a chosen number of sig figs with trailing zeros preserved. All in your browser.

1
Enter a number
Type it exactly as written — trailing zeros matter.
2
See the count
How many sig figs your input has, per the rules.
3
Pick a precision
Use the slider to round to 1–10 sig figs.
4
Check the rules
The rules are summarized right below the result.

Everything is calculated in your browser — nothing is uploaded.

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Free Significant Figures Calculator

Common uses

How It Works

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Frequently Asked Questions