12-hour and 24-hour time
Read, write, and convert time between analogue and digital 12-hour and 24-hour clocks
Ce que l'enfant saura faire ensuite
- Convert 3:45 pm to 15:45 in 24-hour time
- Read 19:30 and state the 12-hour equivalent as 7:30 pm
- Match a set of 12-hour and 24-hour times
1 · Lis
You have used clocks that count 1 to 12, with am for morning and pm for afternoon or evening. There is another way to write time called the 24-hour clock. It counts hours from 00 all the way to 23, so you never need am or pm.
To change an afternoon or evening time into 24-hour time, add 12 to the hour. So 3:45 pm becomes 3 + 12 = 15, which is 15:45. Morning hours before noon stay almost the same. You just add a zero in front if the hour is a single digit, so 9:15 am becomes 09:15.
A train leaves at 19:30. To find the 12-hour time, subtract 12 from the hour: 19 - 12 = 7. So the train leaves at 7:30 pm, in the evening.
Watch out for two special times. Noon is 12:00 pm, and midnight is 00:00 in the 24-hour clock. Neither one follows the usual add-12 or subtract-12 rule.
24-hour time skips am and pm: add 12 to afternoon and evening hours, and keep morning hours almost the same.
À lire aussi
How to Tell Military Time (with Conversion Chart)
Military time is the 24 hour clock in uniform. It counts straight from 00 to 23 with no am or pm. Morning hours look familiar: 8:05 am is 08:05. Afternoon hours add 12: 3:45 pm becomes 15:45 and 7:30 pm becomes 19:30. The chart is your translator. Find the 12 hour time on one side and read the 24 hour match on the other. After a few conversions the adding 12 habit sticks.
3 Ways to Convert from 24 Hour to 12 Hour Time
Going back from 24 hour to 12 hour time undoes the plus 12. Hours 00 to 11 are morning: 08:05 becomes 8:05 am. Hours 12 to 23 are afternoon and evening: subtract 12, so 19:30 becomes 7:30 pm and 20:05 becomes 8:05 pm. Noon is the odd one: 12:40 pm stays 12:40 because noon starts the afternoon at 12, not 0. Midnight is the other odd one: 00:20 is 12:20 am. Learn the two flips plus the two exceptions and matching sets turns easy.
How to Tell Time on a Clock: Easy Steps for Beginners
Every conversion starts with reading the clock right. The short hand names the hour and the long hand counts minutes in fives. At 3:45 the hour hand creeps near 4 while the minutes read 45. Say it first in 12 hour words: quarter to four in the afternoon. Only then convert: afternoon adds 12, giving 15:45. Clean reading first, converting second. Rushing the read guarantees a wrong conversion.
Converting units of time review (seconds, minutes, & hours)
Time conversions stack: seconds into minutes, minutes into hours, hours into day halves. Sixty seconds make a minute and 60 minutes make an hour, but 12 versus 24 hour time is about naming, not regrouping. The same moment wears two labels: 7:30 pm and 19:30. Matching games test both directions at once. Pair each 12 hour card with its 24 hour twin: 9:20 am with 09:20, 12:40 pm with 12:40, 11:55 pm with 23:55. Twins that both check out mean the set is solved.
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