Rounding Calculator

How it works

1. 1In Decimal places mode, the number is scaled by 10ⁿ, rounded half-up, then scaled back — giving a result exact to n decimal places.
2. 2In Nearest multiple mode, the number is divided by the target multiple, rounded, then multiplied back — so 47 to the nearest 5 gives 45.
3. 3Round-half-up breaks ties toward the larger magnitude: 2.5 → 3. This matches everyday arithmetic and most spreadsheet ROUND() functions.

Use cases

• Financial calculations where amounts must be expressed to exactly 2 decimal places (dollars and cents).
• Scheduling tasks that require durations rounded to the nearest 5 or 15 minutes.
• Scientific reporting where a fixed decimal precision is required by a journal or standard.

Frequently asked questions

What is round-half-up vs banker’s rounding?

Round-half-up sends a midpoint like 2.5 up to 3. Banker’s rounding (round-half-to-even) sends it to the nearest even number (2.5 → 2, 3.5 → 4) to reduce bias over large datasets. This calculator uses the familiar round-half-up.

Why does Nearest multiple show — when the multiple is 0?

Dividing by zero is undefined, so no rounding is possible. Enter any non-zero multiple, positive or negative.

Can I round to a fractional multiple like 0.25?

Yes — enter 0.25. The calculation Math.round(value ÷ 0.25) × 0.25 works for any non-zero multiple, including decimals.