Math Tool
Rounding Calculator
Round any number to your chosen precision using different rounding methods.
Rounded number
3.14
Original3.1415900000
Difference0.0015900000
Math Tool
Round any number to your chosen precision using different rounding methods.
Rounded number
3.14
The rounding calculator rounds numbers to a specified precision—whether to the nearest whole number, tenth, hundredth, or any power of ten. It supports three industry-standard rounding methods: round half up (standard banker's rounding), round down (floor), and round up (ceiling). Use it to simplify numbers, prepare data for presentations, or explore how different rounding methods affect your results.
Enter any number, select your target precision from the dropdown, and choose a rounding method. The calculator instantly computes the rounded result and displays the difference from your original number, helping you understand the impact of rounding.
Round half up: multiply by 10^n, round, divide by 10^n. Floor: ⌊x × 10^n⌋ / 10^n. Ceiling: ⌈x × 10^n⌉ / 10^n, where n is the decimal precision.All rounding methods use powers of 10 to shift the decimal point, apply the rounding rule, then shift back. Round half up follows the 0.5 rule (≥0.5 goes up). Floor always rounds down, ceiling always rounds up, regardless of the decimal digit.
| Input | Result | Notes |
|---|---|---|
| 3.14159, round to nearest 0.01 (hundredth) using round half up | 3.14 | The digit 1 is less than 5, so 3.141 rounds down to 3.14. |
| 2.456, round to nearest 0.1 (tenth) using round half up | 2.5 | The digit 6 is ≥ 5, so 2.45 rounds up to 2.5. |
| 1234.567, round to nearest 10 using round down (floor) | 1230 | Floor rounding always goes down, regardless of the next digit. |
Round half up always rounds ≥0.5 upward (e.g., 0.5 → 1). Banker's rounding rounds to the nearest even number when exactly at 0.5 (e.g., 0.5 → 0, 1.5 → 2). This tool uses standard round half up.
Use floor (round down) when you need a conservative lower bound, like inventory counts. Use ceiling (round up) for upper bounds, like calculating required resources or pricing.
Yes. Rounding too early in multi-step calculations introduces cumulative error. Keep full precision in intermediate steps and round only at the end.
Yes. This calculator supports rounding to the nearest 10, 100, or 1000 as well as decimal places.
Rounding to n decimal places: round(x × 10^n) / 10^n. For negative n (e.g., nearest 10), use 10^|n| instead.
Yes. JavaScript numbers are 64-bit floats with ~15–17 significant digits of precision, which covers most practical uses. For arbitrary precision, use a dedicated big-number library.