12-Hour to 24-Hour Converter

Select 12-Hour Time:

HOURS (1–12)

MINUTES (0–59)

24-Hour & Military Time

17:30 24-hour format

🗣️ Pronounced: "Seventeen Thirty Hours"

Military Notation 1730

ISO 8601 Standard 17:30:00

Minutes from Midnight 1,050 mins

1. Convert start time and end time to 24-hour military format.

2. Subtract the starting hours and minutes from the ending hours and minutes.

3. Regroup 60 minutes from the hours if minutes are negative.

Step-by-Step Guide

How to Use This Calculator

STEP 1

01 / 03

Enter 12-Hour Time

Select the hour (1–12), minutes (00–59), and AM or PM.

STEP 2

02 / 03

Instant 24-Hour & Military Output

View the standard 24-hour (HH:MM), 4-digit military (HHMM), and phonetic spoken pronunciation.

STEP 3

03 / 03

Copy Timestamp

Click copy to paste the 24-hour format into schedules, logs, or flight manifests.

Mathematical Proofs

Mathematical Formulas & Rules

12-Hour AM to 24-Hour Rule

12:00 AM → 00:00 (0000 military) | 1:00 AM to 11:59 AM → Hours remain unchanged (e.g. 08:30)

Variable Definitions:

12:00 AM (Midnight) = Converts to 00:00 (0000 in military)

12-Hour PM to 24-Hour Rule

12:00 PM → 12:00 (1200 military) | 1:00 PM to 11:59 PM → Add 12 to Hours (e.g. 5:15 PM = 17:15 / 1715)

Variable Definitions:

Hours + 12 = Add 12 to standard PM hours from 1:00 PM to 11:59 PM

Practical Applications

Worked Calculation Examples

Step-by-step breakdown of common real-world time scenarios, work shifts, and duration math.

Example 1 Verified Math

Midnight (12:00 AM)

Scenario

Converting midnight start of day into 24-hour time.

Calculation: 12:00 AM = 00:00

Result: 00:00 (24-Hour) | 0000 ("Zero Hundred Hours")

Example 2 Verified Math

Midday Noon (12:00 PM)

Scenario

Converting noon midday timestamp.

Calculation: 12:00 PM = 12:00

Result: 12:00 (24-Hour) | 1200 ("Twelve Hundred Hours")

Example 3 Verified Math

Evening (5:45 PM)

Scenario

Converting an evening dinner reservation.

Calculation: 5 + 12 = 17:45

Result: 17:45 (24-Hour) | 1745 ("Seventeen Forty-Five")

Example 4 Verified Math

Late Night (11:59 PM)

Scenario

Converting one minute before midnight.

Calculation: 11 + 12 = 23:59

Result: 23:59 (24-Hour) | 2359 ("Twenty-Three Fifty-Nine")

Reference Table

24-Hour Conversion Matrix

Full 24-hour reference table showing 12-hour AM/PM civilian times alongside 24-hour and military notation.

12-Hour Civilian Time	24-Hour Standard Time	4-Digit Military Time	Spoken Pronunciation
12:00 AM	00:00	0000	Zero Hundred Hundred Hours
1:00 AM	01:00	0100	Zero One Hundred Hours
2:00 AM	02:00	0200	Zero Two Hundred Hours
3:00 AM	03:00	0300	Zero Three Hundred Hours
4:00 AM	04:00	0400	Zero Four Hundred Hours
5:00 AM	05:00	0500	Zero Five Hundred Hours
6:00 AM	06:00	0600	Zero Six Hundred Hours
7:00 AM	07:00	0700	Zero Seven Hundred Hours
8:00 AM	08:00	0800	Zero Eight Hundred Hours
9:00 AM	09:00	0900	Zero Nine Hundred Hours
10:00 AM	10:00	1000	Ten Hundred Hours
11:00 AM	11:00	1100	Eleven Hundred Hours
12:00 PM	12:00	1200	Twelve Hundred Hours
1:00 PM	13:00	1300	Thirteen Hundred Hours
2:00 PM	14:00	1400	Fourteen Hundred Hours
3:00 PM	15:00	1500	Fifteen Hundred Hours
4:00 PM	16:00	1600	Sixteen Hundred Hours
5:00 PM	17:00	1700	Seventeen Hundred Hours
6:00 PM	18:00	1800	Eighteen Hundred Hours
7:00 PM	19:00	1900	Nineteen Hundred Hours
8:00 PM	20:00	2000	Twenty Hundred Hours
9:00 PM	21:00	2100	Twenty-One Hundred Hours
10:00 PM	22:00	2200	Twenty-Two Hundred Hours
11:00 PM	23:00	2300	Twenty-Three Hundred Hours

The Complete Guide to 12-Hour to 24-Hour Time Conversion

The 24-hour clock is the international standard (ISO 8601) for time representation. Unlike the 12-hour system, which repeats numbers twice a day with AM and PM suffixes, the 24-hour system counts continuously from 00:00 (midnight) to 23:59. For the reverse conversion, see our 24-Hour to 12-Hour Converter or explore complete tactical codes on the Military Time Converter.

1. Rules for Converting AM Times

Midnight (12:00 AM): Converts to 00:00 (or 0000 in military time).
1:00 AM to 11:59 AM: The hour digits remain identical. If the hour is a single digit, add a leading zero (e.g. 9:15 AM = 09:15).

2. Rules for Converting PM Times

Noon (12:00 PM): Remains 12:00 (or 1200 in military time).
1:00 PM to 11:59 PM: Add 12 to the hour value: 24-Hour = 12-Hour + 12 (e.g. 7:30 PM = 7 + 12 = 19:30).

After converting your times, compute elapsed intervals with our flagship Time Duration Calculator.

Frequently Asked Questions

How do you convert 12-hour AM/PM time to 24-hour time?

For AM times: 12:00 AM becomes 00:00; for 1:00 AM to 11:59 AM, keep the hour unchanged with a leading zero if under 10 (e.g. 08:30). For PM times: 12:00 PM remains 12:00; for 1:00 PM to 11:59 PM, add 12 to the hour (e.g. 5:15 PM = 17:15).

What is 12:00 AM in 24-hour time?

12:00 AM is 00:00 in standard 24-hour time and 0000 in military time.

What is 11:59 PM in 24-hour time?

11:59 PM is 23:59 in 24-hour time and 2359 in military time.

Mathematical Accuracy & Editorial Review

All calculations on this tool are deterministic and rigorously tested against base-60 modulo arithmetic and US Fair Labor Standards Act (FLSA 29 CFR § 785.48) payroll rounding guidelines.

Reviewed by: Time Mathematics & Payroll Editorial Team Last Updated: April 2026

How to Use This Calculator

Enter 12-Hour Time

Instant 24-Hour & Military Output

Copy Timestamp

Mathematical Formulas & Rules

12-Hour AM to 24-Hour Rule

12-Hour PM to 24-Hour Rule

Worked Calculation Examples

Midnight (12:00 AM)

Midday Noon (12:00 PM)

Evening (5:45 PM)

Late Night (11:59 PM)

24-Hour Conversion Matrix

The Complete Guide to 12-Hour to 24-Hour Time Conversion

1. Rules for Converting AM Times

2. Rules for Converting PM Times

Frequently Asked Questions

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