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Significant Figures Rounding Calculator

Round any number to your desired number of significant figures. Our rounding tool handles trailing zeros correctly using scientific notation when needed.

Sig Fig Rounding Tool

Round any number to a specific number of significant figures

Try These Examples

Click to see how rounding works

📖 How to Round Significant Figures

1
Enter the number you want to round
2
Select how many significant figures you want (1-6)
3
Click "Round" to see the result

Rounding Rules for Chemistry

↑
If digit ≥ 5, round UP
Example: 2.35 → 2.4 (to 2 SF)
↓
If digit < 5, round DOWN
Example: 2.34 → 2.3 (to 2 SF)
⚠
Trailing zeros need special handling
9876 → 9900 (2 SF) is ambiguous, so we write 9.9×10³

Fast rounding targets

Common searches usually mean one of these four jobs.

What this rounding calculator accepts

Use regular decimals or E notation. If you see x 10^n in homework, enter it as E notation.
3500
Whole numbers

Useful for quick homework checks, but trailing zeros may be ambiguous.

35.0056
Decimals

Zeros between non-zero digits stay significant.

3.5e3
E notation

Best for values that should keep a clear sig fig count.

0.00340
Small measurements

Leading zeros are placeholders; the final zero can be significant.

Tricky rounding examples

These are the cases that often cause wrong homework answers.
9.995
3 SF
10.0

Rounding carries into a new digit, so the trailing zero keeps the third sig fig visible.

0.09995
3 SF
0.100

The first significant digit is 9, and the carry creates a measured trailing zero.

1500
2 SF
1.5e+3

Writing 1500 can look ambiguous; E notation shows exactly two significant figures.

1.234e-5
2 SF
1.2e-5

The exponent sets scale, while the coefficient controls the sig fig count.

Rounding
Use this page when the problem says round to 1, 2, 3, or more significant figures.
Counting
Use the counter first when you only need to know how many significant figures a number has.
Calculations
Use the full calculator when an expression must be rounded by addition, subtraction, multiplication, or division rules.

Frequently Asked Questions

How do I round to significant figures?
Enter your number, select how many sig figs you want (1-6), and click 'Round'. The tool will show you the properly rounded result, using scientific notation when needed to avoid ambiguity.
Why does my result show in scientific notation?
When rounding creates trailing zeros (like 9876 → 9900 with 2 sig figs), the result is ambiguous. Scientific notation (9.9e+3) clearly shows exactly 2 significant figures.
What's the rule for rounding when the digit is 5?
In standard scientific rounding, if the digit to drop is 5 or greater, round up. So 2.35 rounded to 2 sig figs becomes 2.4.
Can I round to more sig figs than the original number has?
Technically yes, but it doesn't add real precision. If you have 12 (2 sig figs) and round to 4 sig figs, you get 12.00, but those extra zeros don't represent actual measured precision.

More questions about rounding significant figures

How do you round to significant figures?

Keep the requested number of significant digits, then look at the next digit. If the next digit is 5 or higher, round up. If it is below 5, leave the last kept digit unchanged.

Why does the calculator use scientific notation for some results?

Scientific notation removes trailing-zero ambiguity. For example, 9876 rounded to 2 significant figures is clearer as 9.9e+3 than as 9900.

What does round to 2 significant figures mean?

It means the final answer should keep exactly two meaningful digits. For example, 0.004567 becomes 0.0046 and 9876 becomes 9.9e+3.

What does round to 3 significant figures mean?

It means the final answer should keep three meaningful digits. For example, 123.456 becomes 123, and 3.456e4 becomes 3.46e+4.

Is rounding to significant figures the same as rounding to decimal places?

No. Significant figures count meaningful digits from the first non-zero digit, while decimal places count digits after the decimal point.

Related sig fig resources

Round to 2 significant figuresRound to 3 significant figuresLearn rounding rulesCount significant figuresCompare decimal placesPrint a worksheet

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Use the Full Sig Fig Calculator