Dart & Flutter: Convert a Duration to HH:mm:ss format

Updated: March 31, 2023 By: A Goodman Post a comment

When working with Dart and Flutter, there might be cases where you want to turn a Duration into a string of HH:mm:ss format:

HH: hours (If it is less than 10, there will be a preceding zero)
mm: minutes as 2 digits from 00 to 59

ss: seconds as 2 digits from 00 to 59

Though Dart doesn’t provide an out-of-the-box API that can help us get the job done, we can do it ourselves with only a few lines of code. Let’s create a reusable function called formatDuration as follows:

// Define the function
String formatDuration(Duration duration) {
  String hours = duration.inHours.toString().padLeft(0, '2');
  String minutes = duration.inMinutes.remainder(60).toString().padLeft(2, '0');
  String seconds = duration.inSeconds.remainder(60).toString().padLeft(2, '0');
  return "$hours:$minutes:$seconds";
}

And we can call it like this:

// Try it
void main() {
  const durationOne = Duration(minutes: 900, seconds: 3);
  const durationTwo = Duration(seconds: 19999);
  const durationThree = Duration(days: 2, seconds: 1234);

  print(formatDuration(durationOne));
  print(formatDuration(durationTwo));
  print(formatDuration(durationThree));
}

Output: