Significant Figures Calculator
Count sig figs and round to any precision.
Enter your values
Enter the number you are working with.
Enter the round to how many sig figs you are working with.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Significant figures
- 5
- Rounded to 3 sig figs
- 0.0043
- In scientific notation
- 4.30e-3
- Decimal places in original
- 7
Working
- 1Leading zeros never count; trailing zeros count only after a decimal point.
Quick answer
Significant figures are the digits that carry meaning: all non-zero digits, zeros between them, and trailing zeros after a decimal point.
At a glance
| What it does | Count sig figs and round to any precision. |
|---|---|
| Category | Science |
| Inputs needed | Number, Round to how many sig figs |
| Main output | Significant figures |
| Cost | Free — no sign-up, no download |
How to use the Significant Figures Calculator
- 1Type the number exactly as written, keeping trailing zeros.
- 2Choose how many sig figs to round to.
- 3Read the count and rounded value.
Inputs explained
- Number
- Enter the number you are working with.
- Round to how many sig figs
- Enter the round to how many sig figs you are working with.
Worked example
Using the values the calculator loads with:
Inputs
- Number0.0043020
- Round to how many sig figs3
Results
- Significant figures5
- Rounded to 3 sig figs0.0043
- In scientific notation4.30e-3
- Decimal places in original7
- Leading zeros never count; trailing zeros count only after a decimal point.
Frequently asked questions
Do trailing zeros count?
After a decimal point yes — 2.500 has four sig figs. In a whole number like 2500 they are ambiguous without scientific notation.
Which rule applies to multiplication?
The answer carries the same number of sig figs as the least precise factor. For addition, match decimal places instead.
What do I need to enter into the Significant Figures Calculator?
Just 2 values: number, round to how many sig figs. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Significant Figures Calculator work out the answer?
Significant figures are the digits that carry meaning: all non-zero digits, zeros between them, and trailing zeros after a decimal point. The working is shown step by step so you can verify the result by hand.
Is the Significant Figures Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.