Time Validation Regular Expression

Time validation requires handling both 24-hour and 12-hour formats. The 24-hour format (also known as military time) follows the ISO 8601 standard, while the 12-hour format with AM/PM is commonly used in everyday contexts, particularly in the United States. For complete datetime validation, combine this with date validation.

24-Hour Format (HH:MM or HH:MM:SS)

This pattern validates time in 24-hour format, ranging from 00:00 to 23:59, with optional seconds.

^(?:[01]\d|2[0-3]):[0-5]\d(?::[0-5]\d)?$

Explanation

^ - Start of the string.
(?:[01]\d|2[0-3]) - Hours: 00-09, 10-19 (using [01]\\d) or 20-23 (using 2[0-3]).
: - Colon separator.
[0-5]\d - Minutes: 00-59.
(?::[0-5]\d)? - Optional seconds: colon followed by 00-59. The ? makes the entire group optional.
$ - End of the string.

Implementation

const time24Regex = /^(?:[01]\d|2[0-3]):[0-5]\d(?::[0-5]\d)?$/;
const isValid24HourTime = (time) => time24Regex.test(time);

import re

def is_valid_24_hour_time(time):
  time_regex = r"^(?:[01]\d|2[0-3]):[0-5]\d(?::[0-5]\d)?$"
  return re.match(time_regex, time) is not None

use regex::Regex;

fn is_valid_24_hour_time(time: &str) -> bool {
  let time_regex = Regex::new("^(?:[01]\d|2[0-3]):[0-5]\d(?::[0-5]\d)?$")
    .expect("Could not parse time validation regex");
  time_regex.is_match(time)
}

package main

import (
  "fmt"
  "regexp"
)

func isValid24HourTime(time string) bool {
  timeRegex := "^(?:[01]\d|2[0-3]):[0-5]\d(?::[0-5]\d)?$"
  re := regexp.MustCompile(timeRegex)
  return re.MatchString(time)
}

import Foundation

func isValid24HourTime(_ time: String) -> Bool {
  let timeRegex = "^(?:[01]\d|2[0-3]):[0-5]\d(?::[0-5]\d)?$"
  return NSPredicate(format: "SELF MATCHES %@", timeRegex).evaluate(with: time)
}

using System;
using System.Text.RegularExpressions;

class Application {
  static bool IsValid24HourTime(string time) {
    string timeRegex = "^(?:[01]\d|2[0-3]):[0-5]\d(?::[0-5]\d)?$";
    return Regex.IsMatch(time, timeRegex);
  }
}

import java.util.regex.*;

public class Application {
  public static boolean isValid24HourTime(String time) {
    String timeRegex = "^(?:[01]\d|2[0-3]):[0-5]\d(?::[0-5]\d)?$";
    Pattern pattern = Pattern.compile(timeRegex);
    Matcher matcher = pattern.matcher(time);
    return matcher.matches();
  }
}

<?php
function isValid24HourTime($time) {
  $timeRegex = "^(?:[01]\d|2[0-3]):[0-5]\d(?::[0-5]\d)?$";
  return preg_match("/" . $timeRegex . "/", $time);
}
?>

Test Cases

Time	Valid
00:00
00:00:00
09:30
09:30:45
12:00
12:00:00
23:59
23:59:59
13:45:30
00:59:59
24:00
25:00
12:60
12:30:60
9:30
09:5
9:5
12:00 PM
1200
12:
:30
12:30:5
(empty string)

12-Hour Format with AM/PM

This pattern validates time in 12-hour format with AM/PM designation. It accepts hours from 1-12, minutes from 00-59, optional seconds, and either AM or PM (case-insensitive). The space before AM/PM is optional.

^(?:0?[1-9]|1[0-2]):[0-5]\d(?::[0-5]\d)?\s?[AaPp][Mm]$

Explanation

^ - Start of the string.
(?:0?[1-9]|1[0-2]) - Hours: 1-9 (with optional leading zero using 0?[1-9]) or 10-12 (using 1[0-2]).
: - Colon separator.
[0-5]\d - Minutes: 00-59.
(?::[0-5]\d)? - Optional seconds: colon followed by 00-59.
\s? - Optional whitespace before AM/PM.
[AaPp][Mm] - AM or PM in any case combination (AM, am, PM, pm, etc.).
$ - End of the string.

Implementation

const time12Regex = /^(?:0?[1-9]|1[0-2]):[0-5]\d(?::[0-5]\d)?\s?[AaPp][Mm]$/;
const isValid12HourTime = (time) => time12Regex.test(time);

import re

def is_valid_12_hour_time(time):
  time_regex = r"^(?:0?[1-9]|1[0-2]):[0-5]\d(?::[0-5]\d)?\s?[AaPp][Mm]$"
  return re.match(time_regex, time) is not None

use regex::Regex;

fn is_valid_12_hour_time(time: &str) -> bool {
  let time_regex = Regex::new("^(?:0?[1-9]|1[0-2]):[0-5]\d(?::[0-5]\d)?\s?[AaPp][Mm]$")
    .expect("Could not parse time validation regex");
  time_regex.is_match(time)
}

package main

import (
  "fmt"
  "regexp"
)

func isValid12HourTime(time string) bool {
  timeRegex := "^(?:0?[1-9]|1[0-2]):[0-5]\d(?::[0-5]\d)?\s?[AaPp][Mm]$"
  re := regexp.MustCompile(timeRegex)
  return re.MatchString(time)
}

import Foundation

func isValid12HourTime(_ time: String) -> Bool {
  let timeRegex = "^(?:0?[1-9]|1[0-2]):[0-5]\d(?::[0-5]\d)?\s?[AaPp][Mm]$"
  return NSPredicate(format: "SELF MATCHES %@", timeRegex).evaluate(with: time)
}

using System;
using System.Text.RegularExpressions;

class Application {
  static bool IsValid12HourTime(string time) {
    string timeRegex = "^(?:0?[1-9]|1[0-2]):[0-5]\d(?::[0-5]\d)?\s?[AaPp][Mm]$";
    return Regex.IsMatch(time, timeRegex);
  }
}

import java.util.regex.*;

public class Application {
  public static boolean isValid12HourTime(String time) {
    String timeRegex = "^(?:0?[1-9]|1[0-2]):[0-5]\d(?::[0-5]\d)?\s?[AaPp][Mm]$";
    Pattern pattern = Pattern.compile(timeRegex);
    Matcher matcher = pattern.matcher(time);
    return matcher.matches();
  }
}

<?php
function isValid12HourTime($time) {
  $timeRegex = "^(?:0?[1-9]|1[0-2]):[0-5]\d(?::[0-5]\d)?\s?[AaPp][Mm]$";
  return preg_match("/" . $timeRegex . "/", $time);
}
?>

Test Cases

Time	Valid
12:00 AM
12:00 PM
1:00 AM
1:00 PM
01:00 AM
01:00 PM
9:30 AM
09:30 PM
12:59 AM
11:59 PM
12:00:00 AM
11:59:59 PM
1:30:45 PM
12:00AM
12:00PM
12:00 am
12:00 pm
00:00 AM
13:00 PM
12:60 PM
12:30:60 AM
12:00
9:5 AM
12:00 XM
25:00 PM
(empty string)