How to Use toFixed in JavaScript: Syntax and Examples

In JavaScript, use the toFixed() method on a number to format it as a string with a fixed number of decimal places. For example, num.toFixed(2) returns a string with 2 decimals. This method rounds the number and returns a string, not a number.

Syntax

The toFixed() method is called on a number and takes one optional argument:

• digits (optional): The number of digits to appear after the decimal point. It must be between 0 and 100, inclusive.

The method returns a string representing the number rounded to the specified decimal places.

javascript

number.toFixed(digits)

Example

This example shows how to use toFixed() to format a number with 2 decimal places and how it rounds the number.

javascript

const num = 3.14159;
const formatted = num.toFixed(2);
console.log(formatted);

Output

3.14

Common Pitfalls

Common mistakes include expecting toFixed() to return a number instead of a string, and passing invalid arguments.

• Wrong: Using the result as a number directly can cause unexpected behavior.
• Right: Convert the string back to a number if needed using parseFloat().
• Passing a negative or non-integer argument throws a RangeError.

javascript

const num = 2.5;
const wrong = num.toFixed(2) + 1; // '2.50' + 1 = '2.501'
const right = parseFloat(num.toFixed(2)) + 1; // 2.5 + 1 = 3.5
console.log(wrong);
console.log(right);

Output

2.501
3.5

Quick Reference

Usage	Description
number.toFixed(0)	Rounds to nearest whole number, returns string
number.toFixed(2)	Formats number with 2 decimal places, returns string
parseFloat(number.toFixed(n))	Converts formatted string back to number
number.toFixed()	Defaults to 0 decimal places

Key Takeaways

Use toFixed() to format numbers as strings with fixed decimal places.

toFixed() returns a string, so convert back to number if needed.

The argument must be an integer between 0 and 100; otherwise, it throws an error.

It rounds the number to the specified decimal places.

Avoid adding numbers directly to toFixed() results without conversion.