Rounding Calculator

Round numbers to any decimal place or significant figures with multiple methods

What is Rounding?

Rounding means replacing a number with an approximate value that has a shorter, simpler, or more explicit representation while maintaining its value close to the original.

Common Rounding Types
  • Decimal Places: Rounds to specified digits after decimal point
  • Significant Figures: Rounds to specified meaningful digits
  • Whole Number: Rounds to nearest integer
  • Always Up (Ceiling): Rounds to higher integer
  • Always Down (Floor): Rounds to lower integer
Rounding Methods

Most common rounding method:

  • If the digit after rounding position is ≥5, round up
  • If the digit after rounding position is <5, round down

Example: 3.14159 rounded to 2 decimal places → 3.14 (1 < 5)

Used to minimize rounding bias:

  • If the digit after rounding position is >5, round up
  • If the digit after rounding position is <5, round down
  • If the digit is exactly 5, round to nearest even number

Example: 2.5 → 2, 3.5 → 4

Half Down: Round up if digit >5, else round down

Half Odd: Like half-even but rounds to nearest odd

Toward Zero: Truncate (always toward zero)

Away From Zero: Always away from zero

Common Rounding Examples
Number Rounded to 2 Decimals 3 Significant Figures
3.14159 3.14 3.14
2.71828 2.72 2.72
123.456 123.46 123
0.004567 0.00 0.00457
9876.54321 9876.54 9880
Multiple Rounding Types

Round to decimal places, significant figures, whole numbers, or use ceiling/floor functions.

Various Methods

Choose between common rounding, bankers' rounding, and other specialized methods.

Visual Number Line

See your number's position relative to rounded values on an interactive number line.

About the Rounding Calculator

Our Rounding Calculator is a versatile tool designed to help students, professionals, and anyone needing precise number rounding. Whether you're working with financial data, scientific measurements, or everyday calculations, this calculator provides accurate results with your preferred rounding method.

How to Use This Calculator

  1. Enter the number you want to round
  2. Select the rounding type (decimal places, significant figures, etc.)
  3. Choose the precision level (number of decimal places or significant figures)
  4. Select your preferred rounding method
  5. Click "Round Number" to see the result with explanation

Understanding Rounding Concepts

Rounding is essential in many fields to simplify numbers while maintaining reasonable accuracy:

  • Decimal Places: Counts digits after the decimal point (3.14 has 2 decimal places)
  • Significant Figures: Counts all meaningful digits (0.0045 has 2 significant figures)
  • Whole Numbers: Rounds to the nearest integer (3.7 → 4)
  • Ceiling/Floor: Always rounds up or down regardless of decimal value

Practical Applications of Rounding

Rounding has numerous real-world applications:

  • Finance: Currency calculations typically use 2 decimal places
  • Science: Reporting measurements with appropriate significant figures
  • Engineering: Using practical precision in specifications
  • Statistics: Presenting data in readable formats
  • Everyday Life: Estimating quantities, prices, and measurements

Example Problems

Example 1: Decimal Rounding

Round 7.865 to 2 decimal places using half-up method

Solution:

Look at the third decimal (5):

Since 5 ≥ 5, we round the second decimal up

6 becomes 7

Result: 7.87

Example 2: Significant Figures

Round 0.004567 to 3 significant figures

Solution:

Significant digits are 4,5,6,7

First non-significant digit is 7 (≥5)

Round up the last significant digit (6 → 7)

Result: 0.00457

Example 3: Bankers' Rounding

Round 2.5 to whole number using half-even method

Solution:

Digit after decimal is exactly 5

Nearest even number is 2

Result: 2

Example 4: Ceiling Function

Round 4.2 up to nearest whole number

Solution:

Always rounds up regardless of decimal

Result: 5