Java float vs Double

Differences Between Java float vs Double

The float data type is a single-precision 32-bit IEEE 754 floating-point. The range of values is beyond the scope of this discussion but it is mainly specified in the Floating-Point Types, Formats, and Values section of the Java Language Specification.

The double data type is a double-precision 64-bit IEEE 754 floating-point. Its range of values is beyond the scope of this discussion but is specified in the Floating-Point Types, Formats, and Values section of the Java Language Specification.

A float is mainly used to save memory in large arrays of floating-point numbers. Always we need to remember that data type should never be used for precise values, such as currency.

The double data type is normally the default choice for decimal values. The data type should never be used for precise values, such as currency.

Default Values

Float data type in Java stores a decimal value with 6-7 total digits of precision. So for example 12.12345 can be saved as a float, but 12.123456789 cannot be saved as the float. When representing a float data type in Java we should append the letter f to the end of the data type, otherwise, it will save as double.

Double data type stores decimal values with 15-16 digits of precision. The default value is 0.0d, this means that if you do not append f or d to the end of the decimal, the value will be stored as a double in Java.

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Head to Head Comparison Between Java float and Double (Infographics)

Below are the top 7 comparisons between Java float and Double:

Key Differences Between Java float and Double

Below is the list of points that explain the key difference between float and Double in java:

1. The double data type is more precise than float in Java. By default, floating point numbers are double in Java. In order to store them into float variable, you need to cast them explicitly or suffix with ‘f’ or ‘F’.
2. Float uses 1 bit for sign, 8 bits for exponent and 23 bits for mantissa but double uses 1 bit for sign, 11 bits for exponent and 52 bits for the mantissa.
3. There are some important things we can be taken into consideration while selecting Java float and Double. We might also come across some situations where we need to use particular data type, until and unless if you feel that your result will not fit in float then in this situation you can opt for double.
4. Both Java float and Double are approximate types but differ with memory space and some other things.
5. When you want to compare java and float always prefer Big Decimal and when you are working with Big Decimal constructor you need to use with a string parameter.

Java float and Java Double Comparison Table

Following is the comparison table between Java float and Double.

Conclusion

Though both Java float and Double can be used to represent floating point numbers, there are a couple of things we can consider to choose between Java float and double. Though both Java float vs Double is approximate types, if you need more precise and accurate result then use double. Use float if you have memory constraint because it takes almost half as much space as double. If your numbers cannot fit in the range offered by float then use double. Though be careful with floating point calculation and representation, don’t use double or float for monetary calculation, instead use Big Decimal.

That’s all on the difference between float and double in Java. Remember, by default floating point numbers are double in Java if you want to store them into float variable you need to either cast them explicitly or suffixed them using ‘f’ or ‘F’ character.

Both Java float vs Double is used to represent real numbers in Java i.e. numbers with fractions or decimal points.

You should use a logical operator e.g. > or < to compare both Java float and Double variables, instead of = and ! = because they are not precise.

It’s also best practice to choose a data type which takes less storage if it’s sufficient for data you are storing, so choose float over double if you are happy with precision and range, double is more accurate then float though.

Double and float are not used to represent values those require a very high precision. So for instance to store currency values it is not a good idea to use double or float, instead, Java has a class “Big Decimal” that specifies the exact number of digits following the decimal, including rounding up or down.

Both Double and float data type are used to represent floating point numbers in Java, a double data type is more precise than float. A double variable can provide precision up to 15 to 16 decimal points as compared to float precision of 6 to 7 decimal digits. Another significant difference between float and double in java is their storage requirement, double is more expensive than float. It takes 8 bytes to store a variable while float just takes 4 bytes. This means, if memory is constraint then it is better to use float than double. The double type also has a larger range than float and if your numbers don’t fit well in float then you have to use double in Java. It’s also worth noting that floating point numbers or real numbers are by default double in Java. If you want to store them into float variable, you need to either cast them or use a prefix ‘f’ or ’F’.

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