Java – How to round double / float value to 2 decimal places

In many real-world Java applications, we often need to round numbers—for example, displaying prices in an e-commerce website or calculating salary amounts in a payroll system. In this article, we explore various ways to round double or float values to 2 decimal places. We will cover methods using DecimalFormat, BigDecimal, String.format, and Math.round, so we can choose the best approach based on our needs.

Table of Contents

• 1. DecimalFormat("0.00")
• 2. DecimalFormat("0.00") vs DecimalFormat("#.##")
• 3. Using BigDecimal
• 4. Using String.format("%.2f", input)
• 5. Using Math.round
  • 5.1 Rounding to 2 Decimal Places
  • 5.2 Rounding to 3 Decimal Places
• 6. References

1. DecimalFormat(“0.00”)

We can use DecimalFormat("0.00") to ensure that a number always rounds to 2 decimal places. By default, DecimalFormat uses RoundingMode.HALF_EVEN, but we can change the rounding mode using setRoundingMode(RoundingMode) if needed. For instance, when displaying a salary in our payroll application, we want to ensure the value is consistently formatted.

package com.mkyong.math.rounding;

import java.math.RoundingMode;
import java.text.DecimalFormat;

public class DecimalExample {

  private static final DecimalFormat df = new DecimalFormat("0.00");

  public static void main(String[] args) {

      double input = 1205.6358;

      System.out.println("Original value : " + input);

      // Using DecimalFormat with the default RoundingMode.HALF_EVEN
      System.out.println("Rounded (HALF_EVEN) : " + df.format(input));      // 1205.64

      // Changing to RoundingMode.DOWN
      df.setRoundingMode(RoundingMode.DOWN);
      System.out.println("Rounded (DOWN) : " + df.format(input));      // 1205.63

      // Changing to RoundingMode.UP
      df.setRoundingMode(RoundingMode.UP);
      System.out.println("Rounded (UP) : " + df.format(input));      // 1205.64
  }
}

Output:

Original value : 1205.6358
Rounded (HALF_EVEN) : 1205.64
Rounded (DOWN) : 1205.63
Rounded (UP) : 1205.64

2. DecimalFormat(“0.00”) vs DecimalFormat(“#.##”)

It is important to understand the difference between DecimalFormat("0.00") and DecimalFormat("#.##"). When formatting numbers for display, trailing zeros can be significant. For example, in a financial report, we want to show two decimal places even if the number is whole.

package com.mkyong.math.rounding;

import java.math.RoundingMode;
import java.text.DecimalFormat;

public class DecimalExample2 {

  private static final DecimalFormat dfZero = new DecimalFormat("0.00");
  private static final DecimalFormat dfSharp = new DecimalFormat("#.##");

  public static void main(String[] args) {

      double input = 1205.6;

      System.out.println("Original value : " + input);
      System.out.println("Using 0.00 : " + dfZero.format(input));  // Displays 1205.60
      System.out.println("Using #.## : " + dfSharp.format(input));  // Displays 1205.6

      double input2 = 1205.60;

      System.out.println("\nOriginal value : " + input2);
      System.out.println("Using 0.00 : " + dfZero.format(input2));  // Displays 1205.60
      System.out.println("Using #.## : " + dfSharp.format(input2));  // Displays 1205.6
  }
}

Output:

Original value : 1205.6
Using 0.00 : 1205.60
Using #.## : 1205.6

Original value : 1205.6
Using 0.00 : 1205.60
Using #.## : 1205.6

In scenarios where a consistent two-decimal display is required, such as in invoices or price tags, we recommend using DecimalFormat("0.00").

3. Using BigDecimal

For applications that require high precision, such as financial systems calculating interest or tax, we often use BigDecimal. This approach gives us more control over the rounding mechanism and minimizes errors caused by floating-point arithmetic.

package com.mkyong.math.rounding;

import java.math.BigDecimal;
import java.math.RoundingMode;

public class BigDecimalExample {

  public static void main(String[] args) {

      double input = 1205.6358;
      System.out.println("Original double value : " + input);

      // Convert double to BigDecimal
      BigDecimal salary = new BigDecimal(input);
      System.out.println("BigDecimal value : " + salary);

      // Round to 2 decimal places using RoundingMode.HALF_UP
      BigDecimal salaryRounded = salary.setScale(2, RoundingMode.HALF_UP);
      System.out.println("Rounded BigDecimal value : " + salaryRounded);

      // One-line conversion and rounding
      BigDecimal salaryOneLine = new BigDecimal(input).setScale(2, RoundingMode.HALF_UP);
      System.out.println("One-line rounded BigDecimal : " + salaryOneLine);

      // Convert BigDecimal back to double
      double roundedDouble = salaryOneLine.doubleValue();
      System.out.println("Rounded double value : " + roundedDouble);
  }
}

Output:

Original double value : 1205.6358
BigDecimal value : 1205.63580000000001746229827404022216796875
Rounded BigDecimal value : 1205.64
One-line rounded BigDecimal : 1205.64
Rounded double value : 1205.64

This method is especially useful when we deal with monetary values in a banking or e-commerce application where rounding errors can be critical.

4. Using String.format(“%.2f”, input)

Another simple approach for rounding numbers is by using String.format. This method is excellent for displaying rounded values, such as when showing product prices on a website. However, note that we cannot change the rounding mode—it always rounds using half-up by default.

package com.mkyong.math.rounding;

public class StringFormatExample {

  public static void main(String[] args) {

      double input = 1205.6358;

      System.out.println("Original value : " + input);

      // Using String.format to round to 2 decimal places
      System.out.println("Rounded value : " + String.format("%.2f", input));
      System.out.format("Rounded value : %.2f", input);
  }
}

Output:

Original value : 1205.6358
Rounded value : 1205.64
Rounded value : 1205.64

5. Using Math.round

We also have the option of using Math.round for rounding numbers, which is helpful for educational purposes and simple rounding tasks. For example, if we want to calculate the final price of an item including tax, this method might come in handy.

5.1 Rounding to 2 Decimal Places

package com.mkyong.math.rounding;

public class MathExample {

  public static void main(String[] args) {

      double input = 1205.6358;

      System.out.println("Original value : " + input);

      double roundedSalary = Math.round(input * 100.0) / 100.0;
      System.out.println("Rounded value : " + roundedSalary);
  }
}

Output:

Original value : 1205.6358
Rounded value : 1205.64

5.2 Rounding to 3 Decimal Places

For situations where we need more precision, such as scientific calculations, we can adjust the multiplier accordingly:

double input = 1205.6358;
double roundedValue = Math.round(input * 1000.0) / 1000.0;
System.out.println("Rounded value : " + roundedValue);

Output:

Original value : 1205.6358
Rounded value : 1205.636

6. References

• RoundingMode JavaDoc 11
• Math.round JavaDoc 11
• How to Calculate Monetary Values in Java
• How to Format a Double in Java
• Java String Format Examples