Significant Figures Calculator
How many significant figures a number has as written, rounding to a set number of them, and the right precision for a sum or a product.
Result
Significant figures: 4 significant figures
Type the number exactly as written, since the zeros you write carry meaning.
- Decimal places
- 6
- In scientific notation, keeping its figures
- 4.560 × 10^-3
https://calcgallery.com/algebra-numbers/significant-figures-calculator/
Results follow the mathematical operation and values shown. Check that you selected the intended operation, convention and dataset type before relying on the result. Read the full disclaimer
How to use the Significant Figures Calculator
- Type the number exactly as written, keeping its zeros and decimal point; scientific notation like 1.5e3 works too.
- Choose whether to count its significant figures, round it to a number of them, or combine it with a second number.
- Read the count, any ambiguity in trailing zeros, and the result written to the right precision.
Why the number must be typed as text
1500, 1500. and 1.500 × 10³ are the same value, and a calculator that reads them as numbers cannot tell them apart. Their significant figures, 2, 4 and 4, depend on how they are written. So this page reads what you type, character by character, instead of turning it into a number first.
Rounding
Rounding to n significant figures keeps the first n significant digits and rounds the last one: 3.14159 to three figures is 3.14. Leading zeros are not counted, so 0.004560 to two figures is 0.0046.
With your numbers
- Significant figures: 4; decimal places: 6
Quick reference
Type the number exactly as written, since the zeros you write carry meaning.
| Example | Result |
|---|---|
| 0.004560 | Significant figures: 4 |
| 1500 | Significant figures: 2 |
| 1500. with a point | Significant figures: 4 |
| 1.500e3 | Significant figures: 4 |
| 3.14159 to 3 figures | Result, with the right precision: 3.14 |
| 12.11 × 0.3 | Result, with the right precision: 4 |
Common questions about the Significant Figures Calculator
- What are the rules for significant figures?
- Every non-zero digit counts. Zeros between non-zero digits count. Zeros at the front never count: 0.004560 has four significant figures, 4, 5, 6 and the final 0. Zeros at the end count only if a decimal point is written: 100.0 has four.
- How many significant figures does 1500 have?
- It is ambiguous: two if the zeros are just placeholders, four if they were measured. Writing 1500. with a decimal point, or 1.500 × 10³, makes it four; 1.5 × 10³ makes it two. The page reports both readings for a whole number ending in zeros.
- How do significant figures work in a calculation?
- For multiplication and division, the answer keeps as many significant figures as the least precise input: 12.11 × 0.3 = 3.633, which rounds to 4, one figure like 0.3. For addition and subtraction, it keeps as many decimal places as the input with the fewest: 12.11 + 0.3 = 12.41, which rounds to 12.4.
- Why does rounding 1999 to 2 figures give 2.0 × 10³?
- Because 2000 would be ambiguous: it could be read as one, two, three or four significant figures. Scientific notation shows exactly two.