# Convert Days to Milliseconds in JavaScript Fri Jan 28 20222 min read Photo by Meiying Ng

## Convert days to milliseconds in JavaScript#

To convert days to milliseconds, multiply the days by `24` for the hours, `60` for the minutes, `60` for the seconds and `1000` for the milliseconds, e.g. `days * 24 * 60 * 60 * 1000`.

index.js
```Copied!```function daysToMilliseconds(days) {
// 👇️        hour  min  sec  ms
return days * 24 * 60 * 60 * 1000;
}

console.log(daysToMilliseconds(1)); // 👉️ 86400000
console.log(daysToMilliseconds(2)); // 👉️ 17280000
console.log(daysToMilliseconds(5)); // 👉️ 432000000
``````

We created a reusable function that takes the number of days as parameter and converts the days to milliseconds.

To convert the days to milliseconds, we have to multiply by `24` to convert to hours, `60` to convert to minutes, `60` to convert to seconds and `1000` to convert to milliseconds.

If your application uses fractional units for the days, you might get a decimal number after the conversion.

index.js
```Copied!```function daysToMilliseconds(days) {
// 👇️        hour  min  sec  ms
return days * 24 * 60 * 60 * 1000;
}

console.log(daysToMilliseconds(5.5612)); // 👉️ 442367999.99999
``````

You can use the `Math.round()` function to round the number to the nearest integer.

index.js
```Copied!```function daysToMilliseconds(days) {
// 👇️                   hour  min  sec  ms
return Math.round(days * 24 * 60 * 60 * 1000);
}

console.log(daysToMilliseconds(5.5612)); // 👉️ 442368000
``````

We passed the value to the Math.round function to round to the nearest integer and make sure we don't get a decimal after the conversion.

Here are some examples of how the `Math.round` function works.

index.js
```Copied!```console.log(Math.round(3.49)); // 👉️ 3
console.log(Math.round(3.5)); // 👉️ 4
``````

The function rounds the number up or down to the nearest integer.

If the number is positive and its fractional part is greater than or equal to `0.5`, it gets rounded to the next higher absolute value.

If the number is positive and its fractional portion is less than `0.5`, it gets rounded to the lower absolute value.

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