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Clock times and durations

This page covers two related things: clock times such as 9:30am, and lengths of time such as 2h 15m. Reach for it when you log hours worked, work out when a journey ends, add up meeting lengths, bill by the hour or compare race splits.

Clock times answer “what time is it then?” and durations answer “how long?”. Subtracting two clock times gives a duration, and adding a duration to a clock time gives a new clock time. For calendar dates, see Dates and the calendar; for converting times between places, see Time zones.

Writing clock times

Write times with am or pm, in 24-hour form, as noon and midnight, or the way you’d say them. Case and spacing don’t matter.

calc
9:30am gives 9:30 AM
7.30pm gives 7:30 PM
9 am gives 9:00 AM
21:30 gives 9:30 PM
noon gives 12:00 PM
midnight gives 12:00 AM
half past 7pm gives 7:30 PM
quarter to 5 gives 4:45 AM
  • A dot works as well as a colon with am or pm. 7.30pm and 7:30pm are both half past seven, so you can type times the way you’d write them in a message. Write the minutes as two digits.
  • A time without am or pm is 24-hour. 3:30 and half past 3 are both 3:30 AM. Write 3:30pm, 15:30 or half past 3pm for the afternoon, and use a colon, because 19.30 on its own is a number.
  • Three parts make a duration. 1:30:15 is 1 hour 30 minutes 15 seconds, not a time of day.
  • Units make a duration. 9h is nine hours long, not nine o’clock.

Adding time to a clock time

Add or subtract a duration to find when something starts or ends.

calc
10:30am + 45 minutes gives 11:15 AM
9am + 8.5 hours gives 5:30 PM
6:15am + 7h 50m gives 2:05 PM
12:45pm - 35 minutes gives 12:10 PM
midnight + 90 minutes gives 1:30 AM
11pm + 2 hours gives Tomorrow at 1:00 AM
1am - 2 hours gives Yesterday at 11:00 PM

When the answer crosses midnight it says Tomorrow at or Yesterday at, so you can see the day has changed.

Time between two clock times

Write to between two times to get the time from the first to the second. This is the form to use for shifts, sleep and journeys.

calc
9am to 5pm gives 8 hours
8:45am to 5:15pm gives 8 hours 30 min
9:30 to noon gives 2 hours 30 min
10pm to 6:30am gives 8 hours 30 min
9am to 5pm in minutes gives 480 min

You can also subtract one time from another:

calc
17:00 - 9:00 gives 8 hours
6:30am - 10pm gives 15 hours 30 min

The two forms differ when midnight is involved. to always runs forward, so 10pm to 6:30am is the overnight 8 hours 30 minutes. Subtraction gives the gap between the two times on the same day, whichever order you write them in, so 6:30am - 10pm is 15 hours 30 minutes. For anything that runs past midnight, use to.

Dates with times

Join a date and a time with at, or write the time straight after the date. Adding hours then moves across days properly.

calc
June 14 2025 at 9am gives June 14, 2025 at 9:00 AM
June 14 2025 9:30 gives June 14, 2025 at 9:30 AM
June 14 2025 at 11pm + 2 hours gives June 15, 2025 at 1:00 AM
June 14 2025 at 9am UTC in Berlin gives June 14, 2025 at 11:00 AM

The current time

now is the current time on your Mac. Answers that use it keep up to date while the editor is visible. The answers below are illustrative.

calcAnswers depend on today’s date or live data
now + 1 hour gives 4:47 PM
now to 5pm gives 1 hour 12 min 51 s
now to midnight gives 8 hours 12 min 51 s
hours until midnight gives 8.2141666667 hours
hours since 9am gives 6.7858333333 hours
now + 1 day gives Tomorrow at 3:47 PM
Monday at 10:30 gives Monday 10:30 AM
(11pm + 2 hours) + 1 month gives October 17, 2026 at 1:00 AM

hours until and hours since count to or from a time of day. A time without a date means the next one after until and the most recent one after since, so hours until midnight counts down to tonight and hours since 9am counts from this morning. Swap in minutes for a finer count, or write now to midnight for hours and minutes. For days and weeks, see Counting down.

A time that has rolled into another day, like 11pm + 2 hours, becomes a full date, so you can keep adding calendar units such as months to it.

Writing durations

Write a length of time as a number and a unit. Combine parts by writing them one after another, with or without spaces.

calc
2 hours 30 minutes gives 2 hours 30 min
2h 30m gives 2 hours 30 min
3 hrs 20 mins gives 3 hours 20 min
1h30m15s gives 1 hour 30 min 15 s
2.5 h gives 2.5 hours
1 week 2 days gives 1 week 2 days
1:30:15 gives 01:30:15
Unit You can write
Seconds s, sec, secs, second, seconds
Minutes min, mins, minute, minutes, and m inside a combined duration such as 2h 30m
Hours h, hr, hrs, hour, hours
Days day, days
Weeks wk, wks, week, weeks
Fortnights fortnight, fortnights
Months mo, mos, month, months
Years yr, yrs, year, years
Longer decade, decades, century, centuries, millennium, millennia

Fortnights, decades and centuries work like any other length of time, and adding one to a date moves it by whole calendar periods:

calc
1 fortnight in days gives 14 days
3 decades in years gives 30 years
June 14 2025 + 1 fortnight gives June 28, 2025

A few abbreviations don’t mean what you might expect:

  • m on its own is metres. 5 m is a length. Write 5 min for minutes; m only means minutes after hours, as in 2h 30m.
  • d isn’t a unit. Write 3 days, not 3d.

You can also write a length of time the way you’d say it. Part of an hour comes out in minutes, and a whole with a part comes out in hours and minutes:

calc
half an hour + 20 min gives 50 min
quarter of an hour gives 15 min
three quarters of an hour gives 45 min
an hour and a half gives 1 hour 30 min
a day and a half gives 1 day 12 hours
twenty minutes + half an hour gives 50 min

Adding up and converting durations

Add, subtract, multiply and divide durations like any other number.

calc
1h 45m + 2h 30m gives 4 hours 15 min
45 min + 1 hour 20 min + 35 min gives 2 hours 40 min
2 hours 15 min * 3 gives 6 hours 45 min
90 min / 4 gives 22 min 30 s
37.5 hours / 5 gives 7 hours 30 min

When a result worked out from durations isn’t a whole number of hours, minutes or days, it’s shown in parts, the way you’d say it. A duration you type with a decimal stays as you wrote it, and in hours gives a decimal whenever you want one:

calc
40 hours - 37.5 hours gives 2 hours 30 min
1.5 hours * 3 gives 4 hours 30 min
2.5 hours gives 2.5 hours
40 hours - 37.5 hours in hours gives 2.5 hours

A negative result in several parts is bracketed, so the minus sign clearly covers all of it:

calc
30 min - 2 hours gives -(1 hour 30 min)
10 days - 3 weeks gives -(1 week 4 days)

Multiplying two durations in different units reads the way you’d say it: 5 days × 8 h is eight hours on each of five days. The longer unit counts periods and the shorter one is kept, whichever order you write them in, which makes working hours easy to build up:

calc
working hours in day = 8 h
total days in week = 5 days
working hours in a week = total days in week × working hours in day gives 40 hours
working hours in a month = working hours in a week × 4 gives 160 hours
8 h × 5 days gives 40 hours
5 days × (8 h/day) gives 40 hours
8 hours a day × 5 days gives 40 hours

A rate such as 8 h/day or 8 hours a day works the same way, with or without brackets.

Add in and a unit to convert. A single unit gives a decimal; two units, such as hours and minutes, split the answer.

calc
525 min in hours gives 8.75 hours
525 min in hours and minutes gives 8 hours 45 min
7.8 hours in hours and minutes gives 7 hours 48 min
89.9 min in hours and minutes gives 1 hour 30 min
2 days 3 hours in hours gives 51 hours
100 hours in days and hours gives 4 days 4 hours
18 months in years and months gives 1 year 6 months
200 s in minutes and seconds gives 3 min 20 s

Two-unit answers round to the nearest whole smaller unit, so 89.9 min comes out as 1 hour 30 minutes rather than losing the part minute. For decimal hours, as on a timesheet, write in hours. There’s no separate as decimal hours form.

Weekly totals stay in hours

Hours and minutes add up to hours, however large the total, so a week of shifts reads the way a timesheet does. Days only appear once a day or longer is part of the sum, or when you convert with in days:

calc
7 hours 30 min * 5 gives 37 hours 30 min
7 hours 30 min * 5 in hours gives 37.5 hours
7h 30m * 4 + 1 day gives 2 days 6 hours

Months and years are averages

On their own, a month and a year are average lengths, so converting them to days gives fractions.

calc
1 month in days gives 30.436875 days
1 year in days gives 365.2425 days
1 week in hours gives 168 hours

To add a real calendar month to a date, add it to the date itself: January 31 2025 + 1 month is February 28. See Dates and the calendar.

Durations and hourly rates

Multiplying a duration by an hourly rate gives a price. Write the time however you logged it: a decimal, hours and minutes such as 2h 15m, or a shift written as 9am to 5:30pm. at reads well too.

calc
2.5 hours * $60/hour gives $150.00
3 hours at £45/hour gives £135.00
2h 15m * £40/hour gives £90.00
shift = 9am to 5:30pm
shift * £18/hour gives £153.00
£20/hour * 5 days * 8 h gives £800.00
2 hours 30 min per day * 5 days gives 12 hours 30 min

Days and hours in a longer line still pair up as working days, so £20/hour * 5 days * 8 h is £20 an hour for 40 hours. A duration in parts works in front of per or / too, so a daily habit of 2 hours 30 min per day adds up over the week.

Dividing one duration by another shows how many times it fits, and rounding to a step turns a timesheet entry into billable quarter hours:

calc
3 hours 45 min / 15 min gives 15
1 hour 52 min rounded up to nearest 15 min gives 2 hours

See Rounding hours and minutes for more ways to round a duration.

Timespans, lap times and HMS

A number of seconds can be shown as a readable timespan or as a stopwatch-style lap time.

calc
5000 seconds as timespan gives 1 hour 23 min 20 s
100000 seconds as timespan gives 1 day 3 hours 46 min 40 s
3725 seconds as laptime gives 01:02:05
83.45 seconds as laptime gives 00:01:23.45
2.75 hours as HMS gives 2h 45m 0s

Lap times keep fractions of a second, which suits running, cycling and swimming splits:

calc
0:04:12.50 + 0:04:08.20 gives 00:08:20.7
4 min 5 s * 10 as laptime gives 00:40:50
1:23:45.67 gives 01:23:45.67

A lap time with a fraction of a second needs all three parts: write 0:01:23.45, because 1:23.45 is read as the clock time 1:23 AM.

Angles in hours, minutes and seconds

HMS also converts angles, at 15° per hour, which is how astronomers write right ascension. as DMS (or to DMS) shows an angle in degrees, minutes and seconds, as used for map coordinates. You can type degrees, minutes and seconds directly, with ′ ″ or ' ".

calc
187.5 degrees as HMS gives 12h 30m 0s
51.5074 degrees as DMS gives 51° 30′ 26.64″
51° 30 27 gives 51.5075°
51° 30' 27" gives 51.5075°

Putting it together

Here is a freelancer’s timesheet for a short week, with the invoice total at the end.

calc
mon = 9:15am to 5:45pm
tue = 8:30am to 4:15pm
wed = 10am to 6:30pm
breaks = 3 * 45 min
worked = mon + tue + wed - breaks gives 22 hours 30 min
worked in hours gives 22.5 hours
rate = £45/hour
invoice = worked * rate gives £1,012.50
budget = 30 hours
budget - worked gives 7 hours 30 min

Each day is a shift written with to, and the breaks are taken off the total. The invoice multiplies the hours worked by the rate, and the last line shows how much of the agreed 30 hours is left.