Rounding Calculator
Round, ceil or floor at any digit.
What is the Rounding Calculator?
A tool for computing round, ceil, and floor at any specified digit — not just decimal places, but also tens, hundreds, and other integer place values.
How to use it
Enter a value and a digit. A digit of 2 keeps two decimal places, 0 rounds to an integer, and −2 operates at the hundreds place. Choose round, ceil, or floor, then press Calculate.
Formula & reference
Using a factor factor = 10^digit, the result is round(value × factor) / factor (substituting Math.ceil/Math.floor for ceil/floor mode).
| Digit | Round | Ceil | Floor |
|---|---|---|---|
| 2 | 1234.57 | 1234.57 | 1234.56 |
| 0 | 1235 | 1235 | 1234 |
| −2 | 1200 | 1300 | 1200 |
Round vs. ceil vs. floor vs. banker's rounding — why 0.5 splits opinions
All four methods differ only in how they treat what comes after the specified digit. Round rounds up if the next digit is 5 or greater and down otherwise; ceil always rounds up if anything nonzero remains; floor always truncates whatever follows. These three often agree when the next digit isn't exactly 5, but rounding behavior gets genuinely contested for values that end exactly at .5.
Standard "round half up" (the method this calculator uses) always rounds .5 upward: 0.5→1, 1.5→2, 2.5→3, 3.5→4, 4.5→5. Banker's rounding (round half to even), however, rounds .5 to the nearest even integer: 0.5→0, 1.5→2, 2.5→2, 3.5→4, 4.5→4. The two methods only diverge when the integer part is even (0.5, 2.5, 4.5) — for an odd integer part like 1.5 or 3.5, both methods agree.
This distinction matters in practice because rounding a dataset heavily populated with .5 values always upward with standard rounding introduces a cumulative upward bias. Banker's rounding spreads the rounding direction evenly up and down to cancel out that bias, which is why accounting and statistical software — including some Excel functions and Python 3's built-in round() — adopt it. This calculator uses the simpler, more familiar round-half-up method.