Round to 3 Significant Figures
Rounding to 3 significant figures keeps three leading meaningful digits: 47,386.5 becomes 47,400, and 0.0047386 becomes 0.00474. Three figures is the default precision of engineering and chemistry reporting — the speed of light is quoted as 3.00 × 10^8 m/s and most textbook constants carry exactly three significant figures. All values on this page use standard half-up rounding.
Round to 3 Significant Figures reference last updated · reference source
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What this tool does
Rounding to 3 significant figures keeps three leading meaningful digits: 47,386.5 becomes 47,400, and 0.0047386 becomes 0.00474. Three figures is the default precision of engineering and chemistry reporting — the speed of light is quoted as 3.00 × 10^8 m/s and most textbook constants carry exactly three significant figures. All values on this page use standard half-up rounding.
How to use the Round to 3 Significant Figures
- Check Number to round: 47386.5.
- Check Round to: sigfig.
- Check Significant figures: 3.
- Review the Round to 3 Significant Figures result and its exact-value comparison table.
- Verify assumptions before applying the result.
Formula
Round half up at the chosen precision: decimal places count digits after the point, significant figures count digits that carry meaning from the first nonzero digit, and nearest-multiple rounding snaps to a grid such as the nearest 100.
- x
- Number to round
- mode
- Round to
- places
- Decimal places
- figs
- Significant figures
- multiple
- Nearest multiple of
Ties round half up (away from zero for the magnitude shown in most school contexts); financial rounding rules such as banker's rounding are not applied.
Worked example
Round to 3 Significant Figures: Number to round = 47386.5; Round to = sigfig; Significant figures = 3. Rounding to 3 significant figures keeps three leading meaningful digits: 47,386.5 becomes 47,400, and 0.0047386 becomes 0.00474. Three figures is the default precision of engineering and chemistry reporting — the speed of light is quoted as 3.00 × 10^8 m/s and most textbook constants carry exactly three significant figures. All values on this page use standard half-up rounding.
Inputs
- Number to round47386.5
- Round toSignificant figures
- Decimal places2
- Significant figures3
- Nearest multiple of100
Result
- Rounded value4.74e+4
- As a number47,400
Round to 3 Significant Figures — worked examples
| Number | Rounded |
|---|---|
| 47386.5 | 4.74e+4 |
| 47350 | 4.74e+4 |
| 47349 | 4.73e+4 |
| 0.0047386 | 0.00474 |
| 0.004735 | 0.00473 |
| 9876 | 9.88e+3 |
| 9999 | 1.00e+4 |
| 104950 | 1.05e+5 |
Results explained
- Rounded value
- Rounded value from the formula above. Ties round half up (away from zero for the magnitude shown in most school contexts); financial rounding rules such as banker's rounding are not applied.
- Decimal places
- Decimal places from the formula above. Ties round half up (away from zero for the magnitude shown in most school contexts); financial rounding rules such as banker's rounding are not applied.
Frequently asked questions
Rounding to 3 significant figures keeps three leading meaningful digits: 47,386.5 becomes 47,400, and 0.0047386 becomes 0.00474. The reference table on this page shows 8 worked examples computed with exactly that rule.
When the fourth significant digit is exactly 5 with nothing beyond, half-up sends the value up: 47,350 becomes 47,400, whereas banker's rounding (used by some journals) would leave 47,400 only if the third digit were odd — this page always rounds half up.
Use it for scientific and engineering results, where the measuring instrument typically justifies three digits and any more would overstate the accuracy.
0.0047386 rounds to 0.00474. You can verify it in the table on this page, or type any other value into the calculator above.
Most of the ones on classroom walls: the speed of light as 3.00 × 10^8 m/s, gravitational acceleration as 9.81 m/s², Avogadro's number as 6.02 × 10^23, and the gas constant as 8.31 J/(mol·K). Three figures is the precision at which a constant is accurate enough for nearly all engineering, while still being short enough to memorise and check by hand.
No. Banker's rounding (round-half-to-even) is used in some scientific and financial standards to reduce bias over huge datasets, but this page — and the parent rounding calculator — always rounds a halfway value up, which is the convention taught in schools and used for tax forms.
Yes, with one nuance: the engine rounds halves toward positive infinity, so 47.5 rounds up to 48 at the nearest dollar while -47.5 becomes -47. Away from exact halves, negative values round to the nearest candidate just like positive ones.