Rounding Calculator
Round to any decimal place
About This Calculator
Rounding reduces the precision of a number while keeping it close to the original value. The standard rule is to round up when the digit being dropped is 5 or greater, and round down otherwise. Rounding is essential in measurement, finance, science, and everyday estimation.
Formula
Round to n decimal places: look at the (n+1)th digit
If that digit is >= 5, round up the nth digit; otherwise, round down (truncate)
Example Calculation
Round 3.14159 to various decimal places.
- 1 decimal place: 3.14159 → 3.1
- 2 decimal places: 3.14159 → 3.14
- 3 decimal places: 3.14159 → 3.142
3.1 / 3.14 / 3.142
Rounding Common Constants
| Number | 0 dp | 1 dp | 2 dp | 3 dp | 4 dp |
|---|---|---|---|---|---|
| 3.14159265 | 3 | 3.1 | 3.14 | 3.142 | 3.1416 |
| 2.71828182 | 3 | 2.7 | 2.72 | 2.718 | 2.7183 |
| 1.41421356 | 1 | 1.4 | 1.41 | 1.414 | 1.4142 |
Frequently Asked Questions
What is banker's rounding?
Banker's rounding (round half to even) rounds 0.5 to the nearest even number to reduce statistical bias. For example, 2.5 rounds to 2 and 3.5 rounds to 4.
What is the difference between rounding and truncating?
Truncating simply removes extra digits without looking at the next digit. Rounding considers the next digit and adjusts up if needed. 3.999 truncated to 1 dp is 3.9; rounded it is 4.0.
How do I round to the nearest ten or hundred?
Use negative decimal places. Rounding 4,736 to the nearest hundred means looking at the tens digit (3), which is less than 5, so the result is 4,700.