Rounding Calculator
Enter a number and choose how to round it — to a number of decimal places, to the nearest multiple of any value, or to a number of significant figures.
How the Rounding formula works
Standard rounding (round-half-up) applied at the chosen precision:
Decimal places: round(number × 10ⁿ) / 10ⁿ Nearest multiple: round(number / multiple) × multiple
Step-by-step calculation
- For decimal places, multiply by 10 raised to the number of places, round to the nearest whole number, then divide back down.
- For 'nearest multiple', divide by the multiple, round to the nearest whole number, then multiply back.
Worked example
Rounding 47.386 to 2 decimal places gives 47.39. Rounding 47.386 to the nearest 5 gives 45 (since 47.386/5 ≈ 9.48, which rounds to 9, and 9×5 = 45).
Frequently asked questions
What's the difference between decimal places and significant figures?
Decimal places count digits after the decimal point regardless of the number's size. Significant figures count all meaningful digits in a number, including some before the decimal point — 1,234 rounded to 2 significant figures is 1,200, not 12.34.
How does 'round half up' handle exactly .5?
It rounds any exact halfway value up to the next digit — 2.5 rounds to 3, and −2.5 rounds to −2 (toward positive infinity), which is the most common convention, though some contexts use 'round half to even' instead.