Rounding Calculator
Rounding Calculator
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What is a Rounding Calculator?
A rounding calculator is a mathematical tool that helps you round numbers to a specified precision. Rounding is the process of reducing the number of digits in a number while keeping its value close to the original. This is essential for simplifying calculations, presenting data, and working with measurements.
This calculator offers multiple rounding functions: rounding to decimal places with various modes, rounding to the nearest multiple (like 5, 10, or 100), batch rounding for multiple numbers, and floor/ceiling operations for integer conversion.
Different rounding modes (nearest, up, down, half up, half down, half even) are available for various use cases. Banker's rounding (half even) is particularly useful in financial calculations to avoid systematic bias.
Understanding Rounding Modes
Round to Nearest (Standard)
Rounds to the nearest value. If exactly halfway, rounds up.
Examples: 2.4 → 2, 2.5 → 3, 2.6 → 3
Round Up (Ceiling)
Always rounds toward positive infinity.
Examples: 2.1 → 3, 2.9 → 3, -2.1 → -2
Round Down (Floor)
Always rounds toward negative infinity.
Examples: 2.9 → 2, 2.1 → 2, -2.1 → -3
Banker's Rounding (Half Even)
When exactly halfway, rounds to the nearest even number. Reduces systematic bias in financial calculations.
Examples: 2.5 → 2, 3.5 → 4, 4.5 → 4
Calculator Features
Decimal Rounding
- Round to 0-15 decimal places
- Six different rounding modes
- Shows difference from original
- Copy results to clipboard
Other Functions
- Round to nearest multiple (5, 10, 25, etc.)
- Batch round multiple numbers
- Floor, ceiling, and truncate
- Quick select for common multiples
Frequently Asked Questions
What is the difference between floor and truncate?
For positive numbers, they're the same. For negative numbers, floor rounds toward negative infinity (-2.3 → -3) while truncate removes the decimal part (-2.3 → -2). Truncate always rounds toward zero.
When should I use banker's rounding?
Banker's rounding (half even) is ideal for financial calculations and statistical data. When you round many numbers, standard rounding introduces a slight upward bias. Banker's rounding eliminates this by alternating which way 0.5 values round.
How do I round to the nearest 5 or 10?
Use the Multiple tab. Enter your number, then specify the multiple (5, 10, 25, etc.). For example, 47 rounded to the nearest 10 is 50, and 47 rounded to the nearest 5 is 45.
Can I round multiple numbers at once?
Yes! Use the Batch tab to round multiple numbers simultaneously. Enter your numbers separated by commas, spaces, or newlines, choose your decimal places, and click Round All. You can copy all results at once.
Common Uses of Rounding
Finance & Accounting
- Round currency to 2 decimal places
- Use banker's rounding for fairness
- Round prices to nearest 5 or 10
Science & Engineering
- Match significant figures
- Simplify complex measurements
- Reduce floating-point errors
Everyday Life
- Estimate costs and times
- Simplify mental math
- Round ages and distances
Programming
- Format display values
- Handle floating-point precision
- Create pagination and grouping