Time Format Converter

Convert between 24-hour and 12-hour time formats instantly

Use our dedicated military time converter for instant conversions:

Military Time Converter

Related Time Tools

Military Time Converter Time Now World Clock Time Zones

Frequently Asked Questions

The 12-hour format divides the day into two periods (AM and PM) of 12 hours each, while the 24-hour format counts hours continuously from 00:00 (midnight) to 23:59. The 24-hour format is also called military time in the United States.

Most countries worldwide use the 24-hour format as the standard. The 12-hour format with AM/PM is primarily used in the United States, Canada, Australia, the Philippines, and a few other countries for everyday conversation, though even these countries use 24-hour time in military, medical, and aviation contexts.

Add 12 to the hour for times from 1:00 PM to 11:59 PM. For example, 3:30 PM becomes 15:30 and 9:45 PM becomes 21:45. The exception is 12:00 PM (noon), which stays as 12:00 in 24-hour format.
Written & Reviewed by Experts
SM
Author

Sarah Mitchell, CPA

Certified Public Accountant • 12+ yrs payroll & workforce analytics

Specializes in time management, payroll compliance, and workforce optimization. Helped 500+ businesses streamline time-tracking.

DC
Fact-Checker

David Chen, MBA

Finance & Operations • MBA, Wharton

Specializes in financial modeling, regulatory compliance, and data accuracy verification across payroll and tax systems.

Updated Mar 3, 2026 50+ calculators Expert reviewed
Editorial Policies About Us
Embed This Calculator on Your Website

Time Converter – 12-Hour vs. 24-Hour Time Formats Explained

Converting between 12-hour (AM/PM) and 24-hour time formats is one of the most common time-related tasks, whether you are reading a European train schedule, interpreting a medical record, setting a digital device, or writing code that handles timestamps. This comprehensive guide explains both formats, shows you when to use each, and provides quick-reference tables and conversion shortcuts.

Understanding the Two Formats

The 12-hour clock divides the 24-hour day into two periods: ante meridiem (AM, meaning “before noon”) and post meridiem (PM, meaning “after noon”). Hours run from 12:00 to 12:59, then 1:00 to 11:59, cycling twice per day. The system originated with ancient Egyptians and Romans, who divided daylight and darkness into twelve parts each.

The 24-hour clock counts hours from 00 (midnight) to 23 (11 PM). There is no AM or PM—every time in the day has a unique numerical representation. This system has been used since the early 19th century and is the international standard (ISO 8601).

Conversion Formulas

12-hour to 24-hour:

  • AM times (except 12 AM): Keep the hour, add leading zero if needed. 9:30 AM → 09:30
  • 12:00 AM (midnight): Convert to 00:00
  • PM times (except 12 PM): Add 12 to the hour. 4:15 PM → 16:15
  • 12:00 PM (noon): Keep as 12:00

24-hour to 12-hour:

  • Hours 01–11: Same number + AM. 09:30 → 9:30 AM
  • Hour 00: Convert to 12 AM. 00:45 → 12:45 AM
  • Hour 12: Keep as 12 PM. 12:00 → 12:00 PM
  • Hours 13–23: Subtract 12 + PM. 17:00 → 5:00 PM

Which Countries Use Which Format?

The 24-hour clock is the dominant format in the vast majority of countries worldwide. Here is a breakdown by region:

  • 12-hour (primary): United States, Canada (English-speaking), Australia, New Zealand, Philippines, India (informal), Pakistan, Bangladesh, Malaysia, Colombia, Honduras, and Egypt
  • 24-hour (primary): All of Europe, most of Latin America (Brazil, Argentina, Mexico, Chile), all of East Asia (Japan, China, South Korea), all of Southeast Asia (except Philippines), the Middle East, and all of Africa (except Egypt informally)
  • Mixed usage: The UK, Ireland, and Canada use both formats depending on context. Written schedules and timetables use 24-hour time, while casual speech uses 12-hour.

Common Times in Both Formats

12-Hour 24-Hour Description
12:00 AM00:00Midnight – start of day
1:00 AM01:00Early morning
6:00 AM06:00Typical early wake-up
7:30 AM07:30Common commute start
9:00 AM09:00Business hours begin
12:00 PM12:00Noon – lunch time
1:00 PM13:00Early afternoon
3:30 PM15:30Mid-afternoon
5:00 PM17:00Business hours end
6:30 PM18:30Common dinner time
8:00 PM20:00Prime-time evening
10:00 PM22:00Late evening
11:59 PM23:59Last minute of the day

Conversion Shortcuts

Mental math for time conversion becomes second nature with a few tricks:

  • The “minus 12” rule: For any 24-hour time from 13:00 to 23:59, subtract 12 to get the PM hour. 16:00 − 12 = 4:00 PM.
  • The “subtract 2, drop the 1” shortcut: For times 13–21, take the last digit, subtract 2, and that’s your PM hour. 15:00 → 5 − 2 = 3 → 3:00 PM. For 22 and 23, this still works: 22 → 2 − 2 = 0, but you know 22:00 = 10 PM; 23 → 3 − 2 = 1, 23:00 = 11 PM.
  • Anchor at 18:00: Most people easily remember that 18:00 = 6:00 PM. Work up or down from there.

Worked Examples

Convert 14:45 to 12-hour: 14 − 12 = 2, so 14:45 = 2:45 PM.

Convert 8:20 PM to 24-hour: 8 + 12 = 20, so 8:20 PM = 20:20.

Convert 12:30 AM to 24-hour: 12 AM is a special case—it becomes 00:30.

Programming with Time Formats

When working with time in code, the 24-hour format is almost always preferred. It simplifies sorting, comparison, and arithmetic. Here are common patterns across languages:

  • JavaScript: toLocaleTimeString('en-US', { hour12: false }) outputs 24-hour time. Use { hour12: true } for 12-hour format.
  • Python: datetime.strftime('%H:%M') for 24-hour, '%I:%M %p' for 12-hour.
  • PHP: date('H:i') for 24-hour, date('g:i A') for 12-hour.
  • SQL: TIME_FORMAT(column, '%H:%i') (MySQL) or FORMAT(column, 'HH:mm') (SQL Server).

Always store times internally in 24-hour format or as Unix timestamps. Convert to 12-hour format only at the display layer for users who prefer it. This avoids AM/PM ambiguity in databases and APIs.

The Noon and Midnight Problem

The 12-hour system creates genuine confusion at noon and midnight. Technically, 12:00 PM is noon and 12:00 AM is midnight, but many people get these backwards. Some style guides recommend using “noon” and “midnight” in plain text to avoid ambiguity. The 24-hour system resolves this completely: 00:00 is always midnight, 12:00 is always noon, and there is no possibility of misinterpretation.

When to Use Each Format

  • Use 12-hour for casual communication in the US, Canada, and Australia; for consumer-facing products targeting these markets; and when your audience is unfamiliar with 24-hour time.
  • Use 24-hour for international scheduling, professional and technical contexts, medical records, aviation, military operations, software development, and any situation where ambiguity could cause errors.