Military Time Converter

Two rules convert any clock

Military time is the same clock as the one on your phone with AM and PM taken off. The day runs from 0000 to 2359, every hour gets one name, and no hour is ever named twice. Two rules do all the work. For morning hours, keep the hour and add a leading zero, so 7:05 AM becomes 0705. For afternoon and evening hours, add 12 to the hour, so 3:45 PM becomes 1545 and 9:00 PM becomes 2100. Minutes never change. The State Fire Marshal of North Carolina spells out the same rule on its military time guide: to convert PM times, add 12 to the hour.

Two hours need care, because the number 12 means the start of one half of the day and the end of the other. 12:00 AM, which is midnight, becomes 0000. 12:00 PM, which is noon, stays at 1200. Every other hour follows the two rules with no exceptions. Converting back is the mirror image: if the 24-hour number is 13 or larger, subtract 12 and mark it PM. If it is 12, you have noon. If it is smaller than 12, you have morning.

A chart you can read out loud

Reading military time out loud is the other half of the skill. Hours from 1000 up are spoken as one number, so 1500 is "fifteen hundred" and 2130 is "twenty-one thirty". Below 1000 the leading zero is spoken, so 0700 is "zero seven hundred" and 0945 is "zero nine forty-five". Minutes come out as a pair: "forty-five", "thirty", or "oh five" when the minutes start with a zero. When the minutes are zero, you say "hundred" and stop, which is where "zero hundred hours" for midnight comes from.

Notice what the table does with minutes. They are identical on both clocks, and they are spoken as a two-digit pair, not as a count. Ten past three in the afternoon is 1510 and "fifteen ten", not "fifteen hundred and ten". Radio procedure reads every digit separately for clarity, so 0705 is "zero seven zero five" on the air. Either way, the number on the paper is the same.

0000 and 2400: two names for midnight

0000 and 2400 are the same instant: midnight. The only difference is which side of the day boundary you are writing from. 0000 opens a day. 2400 closes one. A duty log entry that ends at 2400 on Friday means the last moment of Friday, and the entry that starts at 0000 on Saturday means the first moment of Saturday. A report due "at 2400" is due when the day rolls over, not at noon.

Practical systems disagree about which spelling they accept. Many hospitals, airlines and payroll platforms reject 2400 outright and use 0000 for both edges of the day, so every stored timestamp falls inside one day window. Schedules and logbooks are looser and often print 2400 to mark "end of day" next to a column headed "time in" that reads 0000. If you are filling in a form for someone else, use 0000 unless the form asks for the end of the day, and keep a note of which one the system uses.

One more trap: 2400 is not 24:00 in the morning sense, and it does not belong to the day it follows. It belongs to the day that is ending. A shift that runs from 1800 to 2400 is six hours long and finishes at the exact moment the next 0000 begins.

Military time is a clock, not a time zone

Military time is a way of writing an hour, not a place on the map. 1545 means 3:45 PM in every county in the country, and it tells you nothing about where you are or which time zone you are in. Zulu time, written with a Z suffix such as 1545Z, is a different thing: it is Coordinated Universal Time, the time at the prime meridian, and it is what weather forecasts, flight plans and radio calls use. Turning one into the other means knowing your offset from UTC, and that offset moves when daylight saving time starts and ends.

NIST runs time.gov, which shows the official UTC time beside the local time for every zone, and it is the reference to check when a schedule mixes the two. If a dispatch says 1800Z and you are in Chicago, the clock on your wall reads noon in winter (Chicago is 6 hours behind UTC) and 1:00 PM in summer (5 hours behind). If the schedule says plain 1800 with no Z, it is a local time and you read it as 6:00 PM. The letter is the whole difference.

Shifts, watch schedules and the length of a span

A shift is a span, and a span needs two 24-hour times. Subtract the start from the end. When the end number is smaller than the start number, the shift runs through midnight, so add 24 hours to the end first. A 2200 start and a 0600 end is 8 hours, not minus 16.

Watch schedules and rotating shifts work the same way, and they are the reason people learn military time at all. A fire crew working 2200 to 0600 is on nights, and the crew that takes over at 0600 is on days. The handoff happens at 0600, not at 6:00, because nobody has to ask whether it is morning. If a shift has an unpaid meal break, subtract it before you report the span: an eight-hour shift with a 30 minute unpaid lunch is 7.5 hours of work, not 8.

Decimal hours: how a timesheet reads time

Payroll and time clocks do not want "7:45". They want 7.75. Decimal hours are the hours plus the minutes divided by 60, so 45 minutes is 0.75 of an hour and 15:45 is 15.75. Minutes that land on a quarter hour give a clean decimal: 15 minutes is 0.25, 30 minutes is 0.5, and 45 minutes is 0.75. Anything else gives a repeating decimal, which is why most employers round to the nearest quarter hour.

Federal pay rules use the same habit. The Office of Personnel Management rounds pay rates to the nearest cent when it divides an annual salary by hours, and federal timekeeping records tour of duty hours as decimals rather than hours and minutes. The OPM guide on computing rates of pay has the rounding rules. Before you check a pay stub, find out whether your employer rounds each shift, each day or each pay period, because the same 7:52 can land as 7.75, 8.00 or 7.86.

Worked examples end to end

Example 1: the classic conversion. 3:45 PM. The hour is 3 and the period is PM, so add 12 to the hour to get 15, keep the minutes, and write four digits: 1545. Read it as fifteen forty-five. Run it backwards and you take 15, subtract 12 to get 3, and mark it PM, which gives 3:45 PM.

Example 2: a shift length. You clock in at 2200 and out at 0630. The end is smaller than the start, so the shift runs through midnight: 0630 minus 2200 is 8 hours 30 minutes, or 8.50 decimal hours. At $18 an hour that is $153.00 of straight time before any overtime is added.

Example 3: a timecard entry. 15:45 becomes 15 + 45/60 = 15.75 hours. At an hourly rate of $22.50 that is 15.75 x 22.50 = $354.38 for the shift. Write the same span in 12-hour form (3:45 PM) and the number looks much smaller, which is why the decimal version is the one that belongs on a paycheck.

Mistakes that trip people up

Almost every military time mistake comes from one of these, and each one has a one-line fix.

• Dropping the leading zero: 9:00 AM is 0900, not 900. Four digits, always.
• Adding 12 to noon: 12:00 PM is 1200. Only hours 1 through 11 in the afternoon get 12 added.
• Mixing 0000 and 2400: they are the same instant, but systems that only accept 0000 will reject 2400, and logs read 2400 as the end of the day it follows.
• Treating military time as a time zone: 1545 is a clock reading, while 1545Z is UTC. A Zulu time needs a letter and an offset.
• Typing 1545 into a field that wants decimal hours: that field wants 15.75, not 15.45.
• Rounding clock-in times yourself: 7:33 AM can be reported as 7.33, 7.50 or 8.00 depending on the employer rule, so let the system do it.

The North Carolina Office of State Fire Marshal military time guide is a handy one-page reference for the conversion table, time.gov gives the official UTC reference for Zulu conversions, and the Office of Personnel Management pay guide covers the rounding rules that turn decimal hours into money.