CalcFlip Time Data

Complete 24-Hour to 12-Hour Time Conversion Reference Dataset

The most complete open-source time conversion reference dataset available. Every single minute of the 24-hour clock — all 1,440 values — with 12-hour AM/PM equivalents, military time format, spoken pronunciation, and period classification.

Built and maintained by CalcFlip — free instant time converters with no ads and no signup.

What's Inside

File	Description	Records
`time-conversions.json`	All 1,440 24h → 12h conversions	1,440
`military-time.json`	Military time with spoken pronunciation	1,440
`time-periods.json`	Hour classification by time of day	24
`special-cases.json`	Midnight, noon, and edge cases	4
`conversion-rules.json`	The mathematical logic as structured data	6

Quick Start

# Clone the repo
git clone https://github.com/calcflip/calcflip-time-data.git

# Or fetch just the JSON you need
curl https://raw.githubusercontent.com/calcflip/calcflip-time-data/main/time-conversions.json

Data Structure

time-conversions.json

Every minute of the 24-hour clock with its 12-hour equivalent.

{
  "metadata": {
    "total_records": 1440,
    "format_24h": "HH:MM",
    "format_12h": "H:MM AM/PM",
    "source": "ISO 8601 standard",
    "maintained_by": "CalcFlip.com",
    "last_updated": "2026-04-01"
  },
  "conversions": [
    {
      "time_24h": "00:00",
      "time_12h": "12:00 AM",
      "hour_24": 0,
      "minute": 0,
      "period": "AM",
      "period_name": "Midnight",
      "military": "0000",
      "military_spoken": "Zero Hundred Hours",
      "is_special_case": true,
      "special_note": "Midnight — start of day",
      "url": "https://calcflip.com/time/00-00"
    },
    {
      "time_24h": "12:00",
      "time_12h": "12:00 PM",
      "hour_24": 12,
      "minute": 0,
      "period": "PM",
      "period_name": "Noon",
      "military": "1200",
      "military_spoken": "Twelve Hundred Hours",
      "is_special_case": true,
      "special_note": "Noon — midday",
      "url": "https://calcflip.com/time/12-00"
    },
    {
      "time_24h": "18:00",
      "time_12h": "6:00 PM",
      "hour_24": 18,
      "minute": 0,
      "period": "PM",
      "period_name": "Early Evening",
      "military": "1800",
      "military_spoken": "Eighteen Hundred Hours",
      "is_special_case": false,
      "special_note": null,
      "url": "https://calcflip.com/time/18-00"
    }
  ]
}

military-time.json

All military time codes from 0000 to 2359 with full pronunciation data.

{
  "metadata": {
    "standard": "NATO STANAG 2112",
    "format": "HHMM (no colon)",
    "range": "0000-2359",
    "total_records": 1440
  },
  "military_times": [
    {
      "military": "0000",
      "standard_12h": "12:00 AM",
      "standard_24h": "00:00",
      "spoken_en": "Zero Hundred Hours",
      "spoken_es": "Cero cero cero cero horas",
      "spoken_de": "Null Uhr",
      "spoken_fr": "Zéro heure",
      "spoken_pt": "Zero zero zero zero horas",
      "spoken_nl": "Nul uur",
      "period": "Midnight",
      "url": "https://calcflip.com/military-time/0000"
    },
    {
      "military": "0600",
      "standard_12h": "6:00 AM",
      "standard_24h": "06:00",
      "spoken_en": "Zero Six Hundred Hours",
      "spoken_es": "Cero seiscientas horas",
      "spoken_de": "Sechs Uhr",
      "spoken_fr": "Six heures",
      "spoken_pt": "Zero seiscentas horas",
      "spoken_nl": "Zes uur",
      "period": "Early Morning",
      "url": "https://calcflip.com/military-time/0600"
    },
    {
      "military": "1800",
      "standard_12h": "6:00 PM",
      "standard_24h": "18:00",
      "spoken_en": "Eighteen Hundred Hours",
      "spoken_es": "Dieciocho cero cero horas",
      "spoken_de": "Achtzehn Uhr",
      "spoken_fr": "Dix-huit heures",
      "spoken_pt": "Dezoito horas",
      "spoken_nl": "Achttien uur",
      "period": "Early Evening",
      "url": "https://calcflip.com/military-time/1800"
    }
  ]
}

time-periods.json

Classification of each hour by time of day. Useful for scheduling apps, healthcare systems, and shift planning tools.

{
  "periods": [
    { "hour_24": 0,  "period": "Midnight",       "shift": "Night",    "description": "Start of day. Hospital night shifts. Overnight transport." },
    { "hour_24": 1,  "period": "Night",           "shift": "Night",    "description": "Late night. Minimal activity." },
    { "hour_24": 2,  "period": "Night",           "shift": "Night",    "description": "Deep night. Emergency services active." },
    { "hour_24": 3,  "period": "Night",           "shift": "Night",    "description": "Pre-dawn. Lowest human activity period." },
    { "hour_24": 4,  "period": "Pre-Dawn",        "shift": "Night",    "description": "Night shift end. Bakeries open. Early flights." },
    { "hour_24": 5,  "period": "Early Morning",   "shift": "Morning",  "description": "Dawn. Early morning runs. First trains." },
    { "hour_24": 6,  "period": "Early Morning",   "shift": "Morning",  "description": "Sunrise. Military reveille. Early workers." },
    { "hour_24": 7,  "period": "Morning",         "shift": "Morning",  "description": "Breakfast. School start. Morning commute." },
    { "hour_24": 8,  "period": "Morning",         "shift": "Morning",  "description": "Business hours begin. Hospital day shift." },
    { "hour_24": 9,  "period": "Morning",         "shift": "Morning",  "description": "Peak morning productivity." },
    { "hour_24": 10, "period": "Mid-Morning",     "shift": "Morning",  "description": "Mid-morning. High work activity." },
    { "hour_24": 11, "period": "Late Morning",    "shift": "Morning",  "description": "Pre-lunch. Approaching midday." },
    { "hour_24": 12, "period": "Noon",            "shift": "Afternoon","description": "Midday. Lunch. Peak retail activity." },
    { "hour_24": 13, "period": "Early Afternoon", "shift": "Afternoon","description": "Post-lunch. Afternoon shift begins." },
    { "hour_24": 14, "period": "Afternoon",       "shift": "Afternoon","description": "Afternoon. School pickup in some regions." },
    { "hour_24": 15, "period": "Afternoon",       "shift": "Afternoon","description": "Mid-afternoon. Peak traffic begins." },
    { "hour_24": 16, "period": "Late Afternoon",  "shift": "Afternoon","description": "Late afternoon. School ends. Rush hour." },
    { "hour_24": 17, "period": "Early Evening",   "shift": "Evening",  "description": "Evening commute. Business close." },
    { "hour_24": 18, "period": "Early Evening",   "shift": "Evening",  "description": "6 PM. End of standard business day. Military evening formation." },
    { "hour_24": 19, "period": "Evening",         "shift": "Evening",  "description": "Dinner time. Evening news. Restaurant peak." },
    { "hour_24": 20, "period": "Evening",         "shift": "Evening",  "description": "Evening entertainment. Hospital evening shift." },
    { "hour_24": 21, "period": "Night",           "shift": "Night",    "description": "Late evening. Last trains in many countries." },
    { "hour_24": 22, "period": "Late Night",      "shift": "Night",    "description": "Night. Hospital night shift starts. Late pharmacy close." },
    { "hour_24": 23, "period": "Late Night",      "shift": "Night",    "description": "Late night. Approaching midnight." }
  ]
}

special-cases.json

The four time values that require special handling in any conversion system.

{
  "special_cases": [
    {
      "time_24h": "00:00",
      "time_12h": "12:00 AM",
      "common_name": "Midnight",
      "military": "0000",
      "note": "Start of day. 00:00 is midnight, not 12:00 AM in some informal uses. ISO 8601 defines 00:00 as the start of a calendar day.",
      "common_error": "Writing 12:00 AM as 12:00 midnight causes ambiguity. Use 00:00 in 24h systems.",
      "url": "https://calcflip.com/time/00-00"
    },
    {
      "time_24h": "12:00",
      "time_12h": "12:00 PM",
      "common_name": "Noon",
      "military": "1200",
      "note": "Midday. 12:00 PM is noon. The most commonly confused time value globally.",
      "common_error": "12:00 PM is noon, not midnight. 12:00 AM is midnight.",
      "url": "https://calcflip.com/time/12-00"
    },
    {
      "time_24h": "00:01",
      "time_12h": "12:01 AM",
      "common_name": "One minute after midnight",
      "military": "0001",
      "note": "First minute of a new calendar day.",
      "common_error": "Sometimes confused with 12:01 PM. The period is AM.",
      "url": "https://calcflip.com/time/00-01"
    },
    {
      "time_24h": "23:59",
      "time_12h": "11:59 PM",
      "common_name": "One minute before midnight",
      "military": "2359",
      "note": "Last minute of a calendar day. Last valid military time value.",
      "common_error": "Not 12:59 PM. The period is PM but the hour is 11, not 12.",
      "url": "https://calcflip.com/time/23-59"
    }
  ]
}

conversion-rules.json

The complete mathematical logic of 24-hour to 12-hour conversion as structured data. Use this to implement conversion in any programming language.

{
  "rules": [
    {
      "id": 1,
      "name": "Midnight special case",
      "condition": "hour_24 == 0",
      "result_hour_12": 12,
      "result_period": "AM",
      "example": "00:30 → 12:30 AM",
      "note": "Hour 0 in 24h = Hour 12 AM in 12h"
    },
    {
      "id": 2,
      "name": "Morning hours",
      "condition": "hour_24 >= 1 AND hour_24 <= 11",
      "result_hour_12": "hour_24 (unchanged)",
      "result_period": "AM",
      "example": "09:15 → 9:15 AM",
      "note": "Hours 1-11 stay the same, just add AM"
    },
    {
      "id": 3,
      "name": "Noon special case",
      "condition": "hour_24 == 12",
      "result_hour_12": 12,
      "result_period": "PM",
      "example": "12:00 → 12:00 PM",
      "note": "Hour 12 in 24h = Hour 12 PM in 12h"
    },
    {
      "id": 4,
      "name": "Afternoon and evening hours",
      "condition": "hour_24 >= 13 AND hour_24 <= 23",
      "result_hour_12": "hour_24 - 12",
      "result_period": "PM",
      "example": "18:00 → 6:00 PM",
      "note": "Subtract 12 from the hour, add PM"
    },
    {
      "id": 5,
      "name": "Minutes rule",
      "condition": "always",
      "result": "minutes never change",
      "example": "14:37 → 2:37 PM",
      "note": "Minutes are identical in both systems"
    },
    {
      "id": 6,
      "name": "Military time format",
      "condition": "always",
      "result": "HHMM with no colon, zero-padded",
      "example": "6:00 AM → 0600, 6:00 PM → 1800",
      "note": "Military time omits the colon and always uses 4 digits"
    }
  ]
}

Use Cases

This dataset is used by developers and researchers building:

Healthcare scheduling systems — hospitals and clinics globally use 24-hour time for shift management and medication scheduling
Aviation and flight software — international flight scheduling operates entirely on 24-hour time
Military and defense applications — NATO STANAG 2112 requires standardized time communication
Voice assistant applications — converting spoken time queries to structured time values
Shift management tools — factory, retail, and service industry scheduling
International travel apps — helping users understand local time formats
Education platforms — teaching time conversion to students in 12-hour clock countries
Multilingual apps — spoken military time pronunciation in 6 languages included

Conversion Logic (Code Examples)

JavaScript

function convert24to12(time24h) {
  const [hourStr, minuteStr] = time24h.split(':');
  const hour = parseInt(hourStr, 10);
  const minute = minuteStr;

  if (hour === 0)  return `12:${minute} AM`;
  if (hour === 12) return `12:${minute} PM`;
  if (hour < 12)   return `${hour}:${minute} AM`;
  return `${hour - 12}:${minute} PM`;
}

// Examples
convert24to12('00:00') // → '12:00 AM'
convert24to12('12:00') // → '12:00 PM'
convert24to12('18:30') // → '6:30 PM'
convert24to12('23:59') // → '11:59 PM'

Python

def convert_24_to_12(time_24h: str) -> str:
    hour, minute = map(int, time_24h.split(':'))
    minute_str = f"{minute:02d}"

    if hour == 0:  return f"12:{minute_str} AM"
    if hour == 12: return f"12:{minute_str} PM"
    if hour < 12:  return f"{hour}:{minute_str} AM"
    return f"{hour - 12}:{minute_str} PM"

# Examples
convert_24_to_12("00:00")  # → '12:00 AM'
convert_24_to_12("18:30")  # → '6:30 PM'
convert_24_to_12("23:59")  # → '11:59 PM'

PHP

function convert24to12(string $time24h): string {
    [$hour, $minute] = explode(':', $time24h);
    $hour = (int)$hour;

    if ($hour === 0)  return "12:{$minute} AM";
    if ($hour === 12) return "12:{$minute} PM";
    if ($hour < 12)   return "{$hour}:{$minute} AM";
    return ($hour - 12) . ":{$minute} PM";
}

TypeScript

function convert24to12(time24h: string): string {
  const [hourStr, minute] = time24h.split(':');
  const hour = parseInt(hourStr, 10);

  if (hour === 0)  return `12:${minute} AM`;
  if (hour === 12) return `12:${minute} PM`;
  if (hour < 12)   return `${hour}:${minute} AM`;
  return `${hour - 12}:${minute} PM`;
}

Most Searched Time Conversions

Based on live search data from CalcFlip.com:

24-Hour	12-Hour	Military	Live Page
00:00	12:00 AM	0000	calcflip.com/time/00-00
12:00	12:00 PM	1200	calcflip.com/time/12-00
13:00	1:00 PM	1300	calcflip.com/time/13-00
14:00	2:00 PM	1400	calcflip.com/time/14-00
15:00	3:00 PM	1500	calcflip.com/time/15-00
16:00	4:00 PM	1600	calcflip.com/time/16-00
17:00	5:00 PM	1700	calcflip.com/time/17-00
18:00	6:00 PM	1800	calcflip.com/time/18-00
19:00	7:00 PM	1900	calcflip.com/time/19-00
20:00	8:00 PM	2000	calcflip.com/time/20-00
21:00	9:00 PM	2100	calcflip.com/time/21-00
22:00	10:00 PM	2200	calcflip.com/time/22-00
23:00	11:00 PM	2300	calcflip.com/time/23-00

Military Time Pronunciation — 6 Languages

Military	English	Spanish	German	French	Portuguese	Dutch
0000	Zero Hundred Hours	Cero cero cero cero horas	Null Uhr	Zéro heure	Zero zero horas	Nul uur
0600	Zero Six Hundred Hours	Cero seiscientas horas	Sechs Uhr	Six heures	Zero seiscentas horas	Zes uur
1200	Twelve Hundred Hours	Doce cero cero horas	Zwölf Uhr	Douze heures	Doze horas	Twaalf uur
1800	Eighteen Hundred Hours	Dieciocho cero cero horas	Achtzehn Uhr	Dix-huit heures	Dezoito horas	Achttien uur
2000	Twenty Hundred Hours	Veinte cero cero horas	Zwanzig Uhr	Vingt heures	Vinte horas	Twintig uur
2359	Twenty-Three Fifty-Nine Hours	Veintitrés cincuenta y nueve horas	Dreiundzwanzig Uhr neunundfünfzig	Vingt-trois heures cinquante-neuf	Vinte e três horas e cinquenta e nove	Drieëntwintig uur negenenvijftig

Full pronunciation data for all 1,440 values available in military-time.json.

Standards and References

This dataset is built on internationally recognized standards:

ISO 8601 — International standard for date and time representation
NATO STANAG 2112 — NATO standardization agreement for military time
ITU-R TF.460 — UTC and time zone standards used in aviation
IEC 60050-111 — International Electrotechnical Vocabulary for time

Live converter at CalcFlip.com — used by healthcare workers, military personnel, pilots, travelers, and developers worldwide.

Who Uses 24-Hour Time

Understanding which industries and regions use 24-hour time helps developers target the right audiences:

Always 24-hour:

Military and defense (all NATO countries)
Aviation and air traffic control (global)
Maritime navigation
Hospitals and healthcare (most countries)
Railway and transport (Europe, Asia)
Scientific research

Countries using 12-hour in daily life:

United States, Canada, Australia, Philippines, India (informal)

Countries using 24-hour in daily life:

Germany, France, Netherlands, Spain, Portugal, Brazil
Japan, China, Korea
Most of Africa, Middle East, Eastern Europe

Related Tools

All live on CalcFlip.com:

Time Converter — All 1,440 24-hour to 12-hour conversions
Military Time Converter — 0000 to 2359 with pronunciation
Roman Numerals — Numbers 1 to 3000
Temperature Converter — Celsius to Fahrenheit and Kelvin
Age Calculator — Birth year 1924 to 2024

Contributing

Found an error in the data? Open an issue or submit a pull request.

When contributing:

Verify against ISO 8601 or NATO STANAG 2112
Include a source citation
Test conversion logic against the rules in conversion-rules.json

License

MIT License — free to use in personal and commercial projects.

Data sourced from ISO 8601 international standard. Maintained by CalcFlip.com.

Star This Repo

If this data saved you time, give it a ⭐ — it helps other developers find it.

Built with ❤️ by CalcFlip — free instant converters, no ads, no signup.

Name		Name	Last commit message	Last commit date
Latest commit History 3 Commits
LICENSE		LICENSE
README.md		README.md
conversion-rules.json		conversion-rules.json

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Repository files navigation

CalcFlip Time Data

What's Inside

Quick Start

Data Structure

time-conversions.json

military-time.json

time-periods.json

special-cases.json

conversion-rules.json

Use Cases

Conversion Logic (Code Examples)

JavaScript

Python

PHP

TypeScript

Most Searched Time Conversions

Military Time Pronunciation — 6 Languages

Standards and References

Who Uses 24-Hour Time

Related Tools

Contributing

License

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Repository files navigation

CalcFlip Time Data

What's Inside

Quick Start

Data Structure

time-conversions.json

military-time.json

time-periods.json

special-cases.json

conversion-rules.json

Use Cases

Conversion Logic (Code Examples)

JavaScript

Python

PHP

TypeScript

Most Searched Time Conversions

Military Time Pronunciation — 6 Languages

Standards and References

Who Uses 24-Hour Time

Related Tools

Contributing

License

Star This Repo

About

Topics

Resources

License

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