Rounding Calculator
Round a number to any place value with the rounding rule you need.
How to use the Rounding Calculator
- Enter the number.
- Choose the round to.
- Choose the method.
- Press Calculate. The result updates automatically as you type.
About the Rounding Calculator
Rounding shortens a number to a convenient precision while keeping it as close as possible to the original. Measurements, prices and statistics are almost always reported rounded, and the rule you choose matters. The school rule rounds a 5 up. Banker's rounding (half to even) is the default in many spreadsheets' statistical functions and in IEEE floating point because it does not bias large sums upward.
Ceiling and floor are not "nearest" rules at all; they are used when you must not come up short, such as buying whole boxes of tile (round up) or counting completed units (round down). This calculator rounds on the decimal digits you typed, so values like 1.005 round correctly to 1.01 instead of tripping over binary floating-point error.
Formula
Look at the digit just to the right of the place you are rounding to:
- Half away from zero: 5 or more rounds up (away from zero), 4 or less rounds down.
- Half to even: same, except an exact 5 with nothing after it goes to the nearest even digit (2.5 → 2, 3.5 → 4).
- Ceiling / floor / truncate: always up, always down, or simply drop the extra digits.
Example calculation
Using the default values:
- Number = 3.14159
- Round to = Hundredths (0.01)
- Method = Nearest, half away from zero (standard)
the calculator returns:
- Rounded number: 3.14
- Rounding difference: -0.00159
Frequently asked questions
How do I round to the nearest tenth?
Look at the hundredths digit. If it is 5 or more, increase the tenths digit by one; otherwise leave it. 3.14159 → 3.1, and 2.76 → 2.8.
What is banker's rounding?
A rule that rounds exact halves to the nearest even number, so 0.125 rounded to two places is 0.12 and 0.135 is 0.14. It avoids systematic upward bias.
How does rounding negative numbers work?
With the standard rule, −2.5 rounds to −3 (away from zero). Floor rounds −2.5 down to −3; ceiling rounds it up to −2.
Last updated: · Category: Math calculators