Master Number Formatting with toFixed() and parseFloat() in JS

Formatting numbers properly in JavaScript comes up all the time with prices, scores, or measurements. I use two methods constantly: toFixed and parseFloat. I’ll show how to round numbers, format to a specific number of decimals, and safely convert a formatted string back to a number. If you’re brushing up on core flow control too, see do-while.

JavaScript Number Formatting with toFixed

    The method is toFixed – F is capital because JavaScript is case sensitive. It fixes a number to a specific number of decimal places and also rounds the value. Start with a number:

let pi = 3.1414;
let fixedPi = pi.toFixed(2);
console.log(fixedPi); // "3.14"

    If the next digit is 5 or more, it rounds up:

let pi = 3.145634;
let fixedPi = pi.toFixed(2);
console.log(fixedPi); // "3.15" - 4 became 5 because the next digit is 5

    toFixed returns a string, not a number. That’s important if you plan to do arithmetic next.

let pi = 3.1414;
let fixedPi = pi.toFixed(2);
console.log(typeof fixedPi); // "string"

   

JavaScript Number Formatting with parseFloat

    parseFloat – F is capital – converts a numeric string back to a floating-point number.

let str = "3.2323546";
let number = parseFloat(str);
console.log(number);        // 3.2323546
console.log(typeof number); // "number"

    If you’re also working with DOM work alongside number formatting, check out DOM elements.

Combine Methods for JavaScript Number Formatting

    I often use both together to get a rounded number as a true number type. Here’s the pattern:

let original = 7.3423;

// Fix to two decimals (this returns a string), then convert back to number
let rounded = parseFloat(original.toFixed(2));

console.log(rounded);        // 7.34 (number)
console.log(typeof rounded); // "number"

    Because it’s a number, arithmetic works as expected:

console.log(rounded + rounded); // 14.68

    If you skip parseFloat and keep the toFixed result as a string, you’ll get string concatenation instead of arithmetic:

let onlyString = original.toFixed(2);
console.log(onlyString + onlyString); // "7.347.34"

   

Final Thoughts

• toFixed formats to a fixed number of decimals and rounds the value, but returns a string.
• parseFloat converts that string back to a number so you can perform arithmetic safely.
• Use them together when you need both proper formatting and numeric operations.

If you’re cleaning up UI interactions after formatting, see remove DOM.