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Time calculator: add and subtract hours and minutes

Add and subtract hours, minutes and seconds from a list of durations, with the total as H:MM:SS, decimal hours, minutes and seconds.

更新日 検証済みの例：4

H:MM:SS or H:MM, or 2h 15m, 90 min, 1.5 h. Start a line with − to subtract it.
試す
Total
3 h 35 min 45 s
Total: 3 h 35 min 45 s
Total as H:MM:SS
3:35:45
Decimal hours
3.5958h
Total minutes
215.75min
Total seconds
12,945s

The 3 entries add up to 3:35:45 (H:MM:SS), which is 3.5958 hours or 215.75 minutes.

Each entry in hours

Line 11:45:30Line 22:20:15Line 3−30:00
Line by line 行数：3
LineEntrySecondsRunning total
11:45:306,3301:45:30
22:20:158,4154:05:45
3- 0:30:00−1,8003:35:45
計算方法 S

  1. Convert each entry to seconds

    6,330+8,415−1,800=12,945 s6{,}330 + 8{,}415 - 1{,}800 = 12{,}945\ \text{s}

    H:MM:SS → 3600 × H + 60 × MM + SS.

  2. Back to hours, minutes and seconds

    12,945 s = 3:35:45

  3. Decimal hours

    12,9453600=3.595833 h\frac{12{,}945}{3600} = 3.595833\ \text{h}

Time calculator: add and subtract hours and minutesについて

Each line is converted to seconds (3,600 × hours + 60 × minutes + seconds), lines that start with a minus sign are subtracted, and the sum is turned back into hours, minutes and seconds. Entries can be written as H:MM:SS, H:MM, 2h 15m, 90 min or 1.5 h. The total is a duration, not a time of day, so 23:59:59 plus one second gives 24:00:00 rather than wrapping to midnight.

Typical uses are adding up timesheet entries, video clip lengths, lap splits and flight legs. The default list, 1:45:30 plus 2:20:15 minus 0:30:00, totals 3:35:45, which is 3.5958 decimal hours or 215.75 minutes.

Decimal hours are the total seconds divided by 3,600, the form payroll and invoicing systems usually ask for: 7 hours 45 minutes is 7.75 hours. To find the time between a start and an end time of day, use the hours calculator instead.

計算例

Two additions and a subtraction

Durations, one per line
1:45:30 2:20:15 - 0:30:00
Total
3 h 35 min 45 s
Total as H:MM:SS
3:35:45
Decimal hours
3.5958 h

照合元：Python fractions: (6330 + 8415 − 1800) s = 12945 s = 3 h 35 min 45 s; 12945/3600 = 3.5958333…

Carrying past 24 hours

Durations, one per line
23:59:59 0:00:01
Total
1 d
Total as H:MM:SS
24:00:00
Decimal hours
24 h

照合元：86399 + 1 = 86400 s by hand

A negative total

Durations, one per line
1:00 - 2:30
Total
−1 h 30 min
Total as H:MM:SS
−1:30:00
Decimal hours
-1.5 h

照合元：3600 − 9000 = −5400 s by hand

Mixed notations

Durations, one per line
90 min 1.5 h 45 s
Total
3 h 45 s
Total minutes
180.75 min

照合元：5400 + 5400 + 45 = 10845 s; 10845 / 60 = 180.75 by hand

よくある質問

How do I add hours and minutes together?

Add the hours and the minutes separately, then carry every 60 minutes into an hour. 1:45 plus 2:20 gives 3 hours and 65 minutes, and 65 minutes is 1 hour 5 minutes, so the total is 4:05. Seconds carry into minutes the same way. Typing each duration on its own line here does the carrying for you.

How do I convert minutes to decimal hours?

Divide the minutes by 60. 15 minutes is 0.25 hours, 45 minutes is 0.75 hours, so 7 hours 45 minutes is 7.75 hours, and 3:35:45 is 12,945 ÷ 3,600 = 3.5958 hours. When a timesheet rounds to two decimals, each 0.01 hour is 36 seconds, so 3.5958 is entered as 3.60.

How do I convert decimal hours back to hours and minutes?

Keep the whole hours and multiply the decimal part by 60 to get minutes. 1.5 hours is 1 hour 30 minutes, 3.6 hours is 3 hours 36 minutes and 0.1 hours is 6 minutes. Type an entry such as 3.6 h on a line here to see it shown as 3:36:00.

How do I subtract one time duration from another?

Start the line with a minus sign. If the minutes to take away are larger, borrow 60 minutes from the hours: 2:10 minus 0:45 becomes 1:70 minus 0:45, which is 1:25. The total can go below zero; 1:00 minus 2:30 gives −1:30:00, an hour and a half short.

How do I add times in Excel without the total resetting at 24 hours?

Excel stores a time as a fraction of a day, so a plain h:mm format wraps after 24 hours and 25 hours shows as 1:00. Format the total cell with the custom format [h]:mm:ss and the square brackets let hours run past 24. To get decimal hours in Excel, multiply the time by 24.

「Time calculator: add and subtract hours and minutes」の精度はどのくらいですか？

精度は入力値と計算方法の前提に依存します。十進演算には有効数字50桁を使いますが、推定、数値計算手法、元データの精度はそれより低い場合があります。表示の丸め処理でこれらの制約がなくなるわけではありません。 独立した出典の解答と照合した計算例：4。 例えば、「Two additions and a subtraction」はPython fractions: (6330 + 8415 − 1800) s = 12945 s = 3 h 35 min 45 s; 12945/3600 = 3.5958333…と照合しています。

この計算方法の出典は何ですか？

ISO 8601-1:2019 — durations and the extended time format hh:mm:ss; BIPM, The International System of Units (SI), 9th ed. — minute and hour as non-SI units accepted for use with the SI.

この計算機について

T=∑i±(3600 hi+60 mi+si) s,decimal hours=T/3600T = \sum_i \pm (3600\,h_i + 60\,m_i + s_i)\ \text{s},\qquad \text{decimal hours} = T / 3600

出典

  1. ISO 8601-1:2019 — durations and the extended time format hh:mm:ss
  2. BIPM, The International System of Units (SI), 9th ed. — minute and hour as non-SI units accepted for use with the SI

出典と照合済み

この計算機には、独立した出典の解答を使った計算例が 4 件あります。テストに組み込まれており、ここでも実行できます。

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