Does Kotlin have primitive types like Java?

From the developer perspective, no — all types in Kotlin look like objects. However, the Kotlin compiler optimises many types (Int, Double, Boolean, etc.) to Java primitives for performance on the JVM.

What is the difference between Int and Long in Kotlin?

Int holds 32-bit integers (about ±2 billion). Long holds 64-bit integers and uses the L suffix: 1_000_000_000L. Use Long when values may exceed Int range.

Beginner 7 min readKotlin 2.0

Kotlin Data Types — Int, String, Boolean and More

Kotlin is statically typed. Every variable has a type — either inferred or explicit. This tutorial covers all the common Kotlin data types with examples.

What You Will Learn

All numeric types in Kotlin
The Boolean and Char types
How String works in Kotlin
The Any, Unit, and Nothing types
Type conversion between numbers

Overview of Kotlin Data Types

Kotlin has a rich set of built-in types. All types in Kotlin are objects — there are no primitive types visible to developers (though the compiler uses primitives internally for performance).

Common Data Types in Use

kotlin
fun main() {
    val age: Int = 25
    val price: Double = 99.99
    val isActive: Boolean = true
    val grade: Char = 'A'
    val website: String = "KotlinGuide"

    println(age)
    println(price)
    println(isActive)
    println(grade)
    println(website)
}

Output

25 99.99 true A KotlinGuide

Each variable uses an explicit type. In practice, Kotlin infers most types, but writing them explicitly here makes the types easy to see.

Number Types

Kotlin has four integer types and two floating-point types: | Type | Size | Range | |------|------|-------| | Byte | 8-bit | -128 to 127 | | Short | 16-bit | -32,768 to 32,767 | | Int | 32-bit | -2,147,483,648 to 2,147,483,647 | | Long | 64-bit | Very large numbers | | Float | 32-bit | ~7 decimal digits | | Double | 64-bit | ~15 decimal digits | For most everyday numbers, use Int or Double.

Working with Numbers

kotlin
fun main() {
    val count: Int = 1000
    val distance: Long = 9_000_000_000L
    val pi: Double = 3.14159
    val tax: Float = 0.18f

    println(count)
    println(distance)
    println(pi)
    println(tax)
}

Output

1000 9000000000 3.14159 0.18

Underscores in numbers (9_000_000_000) are ignored by the compiler — they just improve readability. L suffix marks a Long literal. f marks a Float.

Beginner Tip: Use Int for whole numbers and Double for decimals unless you have a specific reason to choose another type.

Boolean Type

Boolean has exactly two values: true and false. You use it for conditions, flags, and logic.

Boolean Variables

kotlin
fun main() {
    val isLoggedIn = true
    val hasPermission = false

    println(isLoggedIn)
    println(isLoggedIn && hasPermission)
    println(isLoggedIn || hasPermission)
}

Output

true false true

&& is logical AND (both must be true). || is logical OR (at least one must be true). This is the same as most other languages.

Practice Exercise

Exercisemultiple choice

Which Kotlin type would you use to store the value 3.14?

Quick Quiz

What is the default type Kotlin infers for the literal 42?

Kotlin Data Types — Int, String, Boolean and More

What You Will Learn

Overview of Kotlin Data Types

Common Data Types in Use

Number Types

Working with Numbers

Boolean Type

Boolean Variables

Practice Exercise

Quick Quiz

Frequently Asked Questions

Related Tutorials