Rounding Calculator
2
Mode
Rounded Value3.14
Significant Figures3.1
Rounding replaces a number with a nearby value that has fewer decimal places, trading precision for simplicity. This calculator rounds to any number of decimal places using four selectable methods — standard half-up, always round up (ceiling), always round down (floor), and banker’s rounding — so you can match accounting, scientific, or everyday conventions.
Formula
rounded = round(value × 10^p) / 10^p, where round() follows the selected mode
- value
- The original number being rounded
- p
- Number of decimal places to keep
- mode
- Rule applied at the cut point: normal (half-up), up (ceil), down (floor), or banker’s (half-to-even)
How it works
- Enter the value to round and the number of decimal places to keep (0 keeps a whole number, 2 keeps cents, and so on).
- Choose a rounding mode: Normal rounds to the nearest value with ties going up, Up rounds toward positive infinity (ceiling), Down rounds toward negative infinity (floor), and Banker’s rounds ties to the nearest even digit.
- The value is scaled by 10 to the power of the chosen places, rounded by the selected rule, then scaled back. The result card shows the rounded number.
Worked examples
Round 3.14159 to 2 decimal places using the standard (Normal) method.
- Scale by 10^2: 3.14159 × 100 = 314.159.
- Round to nearest integer: 314 (the digit after .14 is 1, below 5).
- Scale back: 314 / 100 = 3.14.
Rounded value = 3.14
Round 2.5 and 3.5 to 0 decimal places with Banker’s rounding.
- 2.5 sits exactly halfway, so it rounds to the nearest even integer: 2.
- 3.5 also sits halfway, rounding to the nearest even integer: 4.
- Half-to-even keeps long sums unbiased rather than always rounding ties upward.
2.5 → 2 and 3.5 → 4
Frequently asked questions
- What is banker’s rounding and when should I use it?
- Banker’s rounding (round half to even) sends exact halves to the nearest even digit, so 2.5 becomes 2 and 3.5 becomes 4. It prevents the small upward bias that ordinary half-up rounding adds across many values, which is why financial and statistical systems often prefer it.
- How does rounding up differ from standard rounding?
- Standard (Normal) rounding goes to whichever value is closer, with ties going up. The Up mode is a ceiling: it always moves toward positive infinity, so 2.341 rounded up to two places becomes 2.35 even though 2.34 is closer.
- Can I round to whole numbers?
- Yes. Set the decimal places to 0 and the calculator rounds to the nearest integer using your chosen mode. Larger place values are not exposed here, so rounding to the nearest ten or hundred is not built in.
- Does this round to significant figures too?
- This tool rounds to a fixed number of decimal places. To control the number of meaningful digits instead, use the significant figures calculator, which rounds based on the first nonzero digit rather than the decimal point.