Round a Number to 2 Decimal Places in JavaScript

Round a Number to 2 Decimal Places in JavaScript #

Use the toFixed() method to round a number to 2 decimal places, e.g. const result = num.toFixed(2). The toFixed method will round and format the number to 2 decimal places.

index.js

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// ✅ round number to 2 decimal places
const num1 = 13.5748;
const result1 = num1.toFixed(2);
console.log(result1); // 👉️ 13.57
console.log(typeof result1); // 👉️ string

// 👇️ if you need to convert str to float
const final = parseFloat(result1);
console.log(final); // 👉️ 13.57

// ----------------------------------------

// ✅ round number wrapped in string to 2 decimal places

// 👇️ if the value is a string
// call parseFloat to convert it to a number first
const str1 = '13.5758';
const result2 = parseFloat(str1).toFixed(2);
console.log(result2); // 👉️ 13.58
console.log(typeof result2); // 👉️ string

// ----------------------------------------

// 👇️ Convert string back to a number
const num2 = 13.1999;
const result3 = Number(num2.toFixed(2));
console.log(result3); // 👉️ 13.2
console.log(typeof result3); // 👉️ number

The first example uses the Number.toFixed method to round a number to 2 decimal places.

index.js

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const num1 = 13.5748;
const result1 = num1.toFixed(2);
console.log(result1); // 👉️ 13.57
console.log(typeof result1); // 👉️ string

// 👇️ if you need to convert str to float
const final = parseFloat(result1);
console.log(final); // 👉️ 13.57

The only parameter the method takes is the number of digits to appear after the decimal point.

The toFixed method returns a string representation of the number.

In the second example, we have a floating-point number that is wrapped in a string.

index.js

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const str1 = '13.5758';
const result2 = parseFloat(str1).toFixed(2);
console.log(result2); // 👉️ 13.58
console.log(typeof result2); // 👉️ string

// 👇️ if you need to convert str to float
const final = parseFloat(result2);
console.log(final); // 👉️ 13.58

We used the parseFloat function to convert the string to a number because toFixed can only be called on numbers.

You can use the Number object or the parseFloat() function to convert the string that the toFixed method returns into a floating-point number.

index.js

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const num2 = 13.1999;
const result3 = Number(num2.toFixed(2));
console.log(result3); // 👉️ 13.2
console.log(typeof result3); // 👉️ number

const final = parseFloat(num2.toFixed(2));
console.log(final); // 👉️ 13.2

However, notice that the trailing zero was removed after the conversion. This happens because JavaScript doesn't keep insignificant trailing zeros around.

The number 1.00 is the same as 1, so the trailing zeros get dropped when the value is converted to a number.

Note that floating-point numbers don't represent all decimals precisely in binary, which can lead to inconsistent results.

index.js

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console.log(0.1 + 0.2 === 0.3); // 👉️ false

const n1 = (13.555).toFixed(2);
console.log(n1); // 👉️ 13.55

const n2 = (13.5551).toFixed(2);
console.log(n2); // 👉️ 13.56

In the first example 0.1 + 0.2 equals 0.30000000000000004 instead of 0.3. This is because the binary floating-point format cannot accurately represent numbers like 0.1 or 0.2.

The code gets rounded to the nearest number, resulting in a rounding error.

In the second example, we would expect to get 13.56 back, but instead the number gets rounded down to 13.55.

Round a Number to 2 Decimal Places in JavaScript

Round a Number to 2 Decimal Places in JavaScript #

Further Reading #

Borislav Hadzhiev