What is the difference between ceil and floor?

Math.ceil() always rounds up to the next integer (ceiling). Math.floor() always rounds down to the previous integer (floor). Math.round() rounds to the nearest integer.

How do I round to 2 decimal places?

Multiply by 100, round, then divide by 100. Or use toFixed(2). This tool supports rounding to any number of decimal places.

Round Numbers Up / Down — Ceiling & Floor Calculator

Rounding numbers is a fundamental operation in mathematics, programming, finance, and data science. This tool supports four rounding methods — round to nearest, ceiling (always round up), floor (always round down), and truncation (toward zero) — with configurable decimal precision from 0 to 15 places.

Rounding Methods Explained

Round (nearest): Rounds to the closest value. 2.5 → 3, 2.4 → 2. Standard mathematical rounding.
Ceiling (ceil): Always rounds up toward positive infinity. 2.1 → 3, -2.9 → -2.
Floor: Always rounds down toward negative infinity. 2.9 → 2, -2.1 → -3.
Truncate: Removes the decimal part without rounding. 2.9 → 2, -2.9 → -2.

Rounding with Decimal Places

When rounding to 2 decimal places (for example), the same methods apply but at the hundredths position. 3.14159 rounded to 2 places = 3.14 (nearest), 3.15 (ceiling), 3.14 (floor).

Frequently Asked Questions

What is banker's rounding?

Banker's rounding (round half to even) rounds 0.5 to the nearest even number: 2.5 → 2, 3.5 → 4. This reduces cumulative rounding bias in large datasets. This tool uses standard rounding (round half up).

Why does 1.005 round to 1 instead of 1.01?

This is a floating-point representation issue. 1.005 cannot be represented exactly in binary, so it is stored as slightly less than 1.005, causing it to round down. Use a proper decimal library for financial calculations.

Number Rounder online

Round numbers up, down, or to nearest with custom decimal precision — runs in your browser

Rounding Methods Explained

Rounding with Decimal Places

Frequently Asked Questions

What is banker's rounding?

Why does 1.005 round to 1 instead of 1.01?