# Significant Figures Calculator

URL: https://speedycalculator.com/calculators/math/significant-figures/
Last updated: 2026-10-25

> The significant figures calculator rounds a number to a chosen number of significant digits, as required in science and engineering reports. It also shows the result in scientific notation.

## Inputs

- Number
- Significant figures

## Results

- Rounded
- Scientific coefficient
- Power of ten

## Formula

```
Rounded = round(x, s − 1 − floor(log₁₀|x|))
```

## Explanation

Significant figures express how precisely a quantity is known. Leading zeros are never significant.

### How to use the Significant Figures Calculator

- **Number**
- **Significant figures**

Results update as you type, and every field accepts the units shown in its menu.

### How it works

Find the position of the first non-zero digit using log₁₀, then round to the requested number of digits from there.

### Inputs explained

FieldWhat to enterNumberA numberSignificant figuresA number

### What each result means

- **Rounded** = round([Number], [Significant figures] - 1 - [Magnitude])
- **Scientific coefficient** = round([Number] ÷ 10^[Magnitude], [Significant figures] - 1)
- **Power of ten** = [Magnitude]

### Example values

How the main result changes when **Number** changes and everything else stays at the example values above:

NumberRounded0.00230.00230.00340.00340.00460.00460.00570.00570.00690.00690.00910.0091

## Worked example

Inputs — Number: 0.00456789; Significant figures: 3.

Results — **Rounded = 0.00457**; Scientific coefficient = 4.57; Power of ten = -3.

## FAQ

**Are trailing zeros significant?**
After a decimal point, yes: 2.50 has three significant figures.

**How many significant figures in 1200?**
Ambiguous; write 1.2 × 10³ or 1.200 × 10³ to be clear.

**What formula does the Significant Figures Calculator use?**
Rounded = round(x, s − 1 − floor(log₁₀|x|)).