Round a Date to the nearest 5 Minutes using JavaScript

Round a Date to the nearest 5 Minutes using JavaScript #

To round a date to the nearest 5 minutes:

1. Convert 5 minutes to milliseconds.
2. Divide the date's value in milliseconds by the result from the conversion.
3. Pass the result to the Math.round() function.
4. Multiply by the number of milliseconds in 5 minutes.

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function roundToNearest5(date = new Date()) {
  const minutes = 5;
  const ms = 1000 * 60 * minutes;

  // 👇️ replace Math.round with Math.ceil to always round UP
  return new Date(Math.round(date.getTime() / ms) * ms);
}

// 👇️ Sun Jan 16 2022 08:15:00 (minutes are 13)
console.log(roundToNearest5(new Date(2022, 0, 16, 8, 13, 00)));

// 👇️ Sun Jan 16 2022 08:10:00 (minutes are 12)
console.log(roundToNearest5(new Date(2022, 0, 16, 8, 12, 00)));

We used the Date() constructor when logging the examples to the console. The parameters we passed are: year, month (January = 0, February = 1, etc), day of month, hours, minutes, seconds.

We created a reusable function that rounds a date to the nearest 5 minutes.

If you always want to round up, replace the Math.round() function with Math.ceil().

The ms variable stores the number of milliseconds there are in 5 minutes.

The getTime method returns the number of milliseconds since the Unix Epoch.

We divide the result by the number of milliseconds in 5 minutes and round to the nearest integer using the Math.round function.

Here are some examples of how Math.round works.

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console.log(Math.round(0.49)); // 👉️ 0
console.log(Math.round(0.5)); // 👉️ 1

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

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

If you always want to round up to the next 5 minutes, use the Math.ceil function instead.

Copied!
function roundToNearest5(date = new Date()) {
  const minutes = 5;
  const ms = 1000 * 60 * minutes;

  return new Date(Math.ceil(date.getTime() / ms) * ms);
}

// 👇️ Sun Jan 16 2022 08:15:00 (minutes are 13)
console.log(roundToNearest5(new Date(2022, 0, 16, 8, 13, 00)));

// 👇️ Sun Jan 16 2022 08:15:00 (minutes are 12)
console.log(roundToNearest5(new Date(2022, 0, 16, 8, 12, 00)));

The Math.ceil function returns the smallest integer that is greater than or equal to the provided number.

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console.log(Math.ceil(0.1)); // 👉️ 1
console.log(Math.ceil(5.0001)); // 👉️ 6

In short, if there is anything after the decimal, the number will get rounded to the next integer, otherwise the number is returned.

The last step is to multiply the value from calling Math.round or Math.ceil with the number of milliseconds there are in 5 minutes and pass the result to the Date() constructor.

The roundToNearest5 function returns a new Date object with the minutes rounded to the nearest 5.