Rounding Calculator

Round numbers to nearest integer, decimal places, significant figures, or round up/down with our free rounding calculator

Available Calculators

What is Rounding?

Rounding is the process of approximating a number to a specified precision. It's used to simplify numbers, make calculations easier, and present results in a more readable format. Common rounding methods include rounding to the nearest integer, to a specific number of decimal places, or to significant figures.

Rounding Rules

The standard rounding rule: if the digit to be removed is 5 or greater, round up. If it's less than 5, round down. For rounding up (ceiling), always round to the next higher integer. For rounding down (floor), always round to the previous lower integer.

Rounding Formula

To round a number to n decimal places:

round(x, n) = ((x × 10^n + 0.5) ÷ 10^n)

Examples of Rounding Calculations

Here are several everyday situations that show how easy it is to use our rounding calculator.

Example 1: Round to Nearest Integer

Round 3.7 to the nearest integer.

You can use our calculator by entering:

What is 3.7 rounded to the nearest integer?

The calculator returns: 4

Decimal part: 0.7
Since 0.7 ≥ 0.5, round up
Result: 4

The formula used is:

round(3.7) = 4

Example 2: Round to 2 Decimal Places

Round π (3.14159) to 2 decimal places.

You can use our calculator by entering:

What is 3.14159 rounded to 2 decimal places?

The calculator returns: 3.14

Multiply by 100: 3.14159 × 100 = 314.159
Round: 314
Divide by 100: 3.14

The formula used is:

round(3.14159, 2) = 3.14

Example 3: Round to 3 Significant Figures

Round 123.456 to 3 significant figures.

You can use our calculator by entering:

What is 123.456 rounded to 3 significant figures?

The calculator returns: 123

First 3 digits: 123
Next digit is 4 (< 5), so round down
Result: 123

The formula used is:

round(123.456, 3 sig. fig.) = 123

Example 4: Round Up for UK Pricing

A product at Tesco costs £19.99. Round up to determine the price ceiling.

You can use our calculator by entering:

What is 19.99 rounded up?

The calculator returns: 20

Always round up to the next integer
Result: 20

The formula used is:

19.99 = 20

Example 5: Round Down for UK Capacity

You have 47.8 litres of water. How many full 5-litre containers can you fill?

You can use our calculator by entering:

What is 47.8 ÷ 5 rounded down?

The calculator returns: 9

47.8 ÷ 5 = 9.56
Round down: 9 full containers

The formula used is:

9.56 = 9

Example 6: UK Currency Rounding

Round £12.345 to 2 decimal places for UK currency display.

You can use our calculator by entering:

What is 12.345 rounded to 2 decimal places?

The calculator returns: 12.35

Third decimal is 5, so round up
Result: 12.35

The formula used is:

round(12.345, 2) = 12.35

Example 7: Scientific Notation

Round 0.0001234 to 2 significant figures.

You can use our calculator by entering:

What is 0.0001234 rounded to 2 significant figures?

The calculator returns: 0.00012

First 2 significant digits: 12
Next digit is 3 (< 5), so round down
Result: 0.00012

The formula used is:

round(0.0001234, 2 sig. fig.) = 0.00012

Example 8: Percentage Rounding

Round 33.333% to 1 decimal place.

You can use our calculator by entering:

What is 33.333 rounded to 1 decimal place?

The calculator returns: 33.3

Second decimal is 3 (< 5), so round down
Result: 33.3

The formula used is:

round(33.333, 1) = 33.3

Example 9: Measurement Rounding

Round 15.678 cm to 1 decimal place for a measurement.

You can use our calculator by entering:

What is 15.678 rounded to 1 decimal place?

The calculator returns: 15.7

Second decimal is 7 (≥ 5), so round up
Result: 15.7

The formula used is:

round(15.678, 1) = 15.7

Example 10: Large Number Rounding

Round 1,234,567.89 to the nearest thousand.

You can use our calculator by entering:

What is 1,234,567.89 rounded to the nearest thousand?

The calculator returns: 1,235,000

Look at the hundreds digit: 5
Since 5 ≥ 5, round up
Result: 1,235,000

The formula used is:

round(1234567.89, -3) = 1235000

Summary

These examples show how our rounding calculator can handle:

  • •Rounding to nearest integer (3.7 → 4)
  • •Rounding to decimal places (3.14159 → 3.14)
  • •Rounding to significant figures (123.456 → 123)
  • •Rounding up and down for practical applications

You can adapt any real-life situation involving rounding to one of these patterns and let the calculator do the work for you.

How to Use

  1. Select the type of rounding you need (nearest integer, decimal places, significant figures, round up, or round down).
  2. Enter the number and any required parameters (e.g., number of decimal places).
  3. View the result and step-by-step calculation breakdown.

Frequently asked questions

How do I round to the nearest integer?

To round to the nearest integer, look at the decimal part. If it's 0.5 or greater, round up. If it's less than 0.5, round down. For example, 3.7 rounds to 4, and 3.2 rounds to 3.

What is the difference between rounding and truncating?

Rounding considers the value of the digits being removed and adjusts accordingly. Truncating simply removes digits without any adjustment. For example, rounding 3.7 gives 4, while truncating gives 3.

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About this tool

Published by Online Tools Center

Last updated:

Check the units, assumptions and rounding before using a result. Health and financial estimates are educational and do not replace individual professional advice.

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