Int, Long, Float, Double number types in Kotlin

Introduction

We use different number types to store numbers in the best way for our program. Each type holds numbers of different sizes and with or without decimals.

When you need to store whole numbers that fit in a small range, use Int.

When you need to store very big whole numbers, use Long.

When you need to store numbers with decimals and less precision, use Float.

When you need to store numbers with decimals and more precision, use Double.

When you want to save memory by choosing the smallest type that fits your number.

Syntax

Kotlin

val myInt: Int = 123
val myLong: Long = 1234567890123L
val myFloat: Float = 12.34F
val myDouble: Double = 12.3456789

Use L suffix for Long numbers to tell Kotlin it is a Long.

Use F suffix for Float numbers to tell Kotlin it is a Float.

Examples

This stores a whole number without decimals in an Int variable.

Kotlin

val age: Int = 30

This stores a very large whole number using Long. The L is needed.

Kotlin

val distance: Long = 9876543210L

This stores a decimal number with less precision using Float. The F is needed.

Kotlin

val price: Float = 19.99F

This stores a decimal number with more precision using Double.

Kotlin

val pi: Double = 3.1415926535

Sample Program

This program shows how to declare and print Int, Long, Float, and Double variables.

Kotlin

fun main() {
    val myInt: Int = 100
    val myLong: Long = 10000000000L
    val myFloat: Float = 10.5F
    val myDouble: Double = 10.123456789

    println("Int value: $myInt")
    println("Long value: $myLong")
    println("Float value: $myFloat")
    println("Double value: $myDouble")
}

Important Notes

Int and Long store whole numbers only, no decimals.

Float and Double store decimal numbers, but Double is more precise.

Always use suffix L for Long and F for Float to avoid errors.

Summary

Int is for normal whole numbers.

Long is for very big whole numbers.

Float is for decimal numbers with less precision.

Double is for decimal numbers with more precision.