JavaScript Math ceil()

The ceil() method rounds a decimal number up to the next largest integer and returns it. That is, 4.3 will be rounded to 5 (next largest integer).


let number = Math.ceil(4.3);

// Output: 5

ceil() Syntax

The syntax of the Math.ceil() method is:


Here, ceil() is a static method. Hence, we are accessing the method using the class name, Math.

ceil() Parameter

The ceil() method takes in a single parameter:

  • number - value that is rounded off to its nearest largest integer

ceil() Return Value

The ceil() method returns:

  • the nearest largest integer after rounding off the specified number
  • NaN (Not a Number) for a non-numeric argument

Example 1: JavaScript Math.ceil() with Positive Numbers

let result1 = Math.ceil(23.8);
// Output: 24

let result2 = Math.ceil(87.1);
// Output: 88

Here, we have used the ceil() method to round decimal values, 23.8 to 24 and 87.1 to 88.

Example 2: Math.ceil() with Negative Numbers

let result1 = Math.ceil(-3.8);
// Output: -3

let result2 = Math.ceil(-7.1);
// Output:  -7

Here, Math.ceil() rounds the number -3.8 to -3 because mathematically, -3 is larger than -3.8. Similarly, the method rounds -7.1 to -7.

Example 3: Math.ceil() with Numeric String

// ceil() with a numeric string let number3 = Math.ceil("2.490");
console.log(number3); // Output: 3

Here, we have used the numeric string "2.490" with the ceil() method. In this case, the numeric string is converted to a number.

Then, the method rounds the number to its next largest integer, 3.

Example 4: Math.ceil() with Non-Numeric Argument

// ceil() with string as argument let value = Math.ceil("JavaScript");
console.log(value); // Output: NaN

In the above example, we have tried to calculate the sign of the string "JavaScript". Hence, we get NaN as the output.

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