Add and subtract durations line by line
Each line holds one duration in hours and minutes plus its own operator, so a mixed sheet such as 7:45, 8:20 and minus 0:30 totals itself as you type. Blank lines stay out of the sum, and the running result shows the signed total in H:MM, in decimal hours and in plain minutes. Use Add row for another line and the × button to remove one. Half-filled lines are flagged with the nearest explanation instead of being counted as zero, and the result stays marked incomplete until every line is valid or cleared.
Durations are not clock times
A clock calculator answers "when does this shift end?"; this page answers "how much time in total?". That difference removes the 24-hour ceiling: 48:30 plus 2:45 is 51:15, a duration no wall clock can display. Weekly timesheet lines, accrued leave balances and project budgets all cross midnight freely. Negative results are equally legitimate: subtracting 1:30 from 1:00 leaves -0:30, which is how a correction or an over-deduction reads before you fix the source line.
Minutes are exact — decimals are a display
The arithmetic keeps whole minutes end to end, so 1:45 plus 0:30 is exactly 2:15 and never 2.29 or 2.3. Decimal hours are a presentation of the same total: divide the minutes by 60, so 1:30 is 1.50 hours — not 1.30, which would be one hour eighteen minutes. The built-in converter works both ways and only accepts decimal values that land on whole minutes; 45.5 hours converts cleanly, while 45.33 is refused with the exact minute count it represents rather than silently rounded.
Worked example: reconciling a corrected week
Suppose a week reads 7:45, 8:10, 8:00, 9:05 and 6:30, and payroll has already deducted a 30-minute break that your records show as paid. Enter the five lines as a plus, then add back the wrongly deducted 0:30 as one more plus line (or subtract it from a minus line, whichever reads clearer on your sheet). The five shifts total 39:30, so the corrected record is 40:00 — the signed total shows that figure beside every line, and copying the summary keeps the adjustment visible so a reviewer can trace it to its line number instead of trusting an unexplained final number.
Limits, errors and privacy
Lines are capped at 50 with hours up to 9,999 per line and minutes 0–59, which keeps every total a safe whole number. Non-numeric or out-of-range values are named by field. The sheet saves in this browser only — one storage profile for this tool, separate from every other calculator on the site — and Reset clears it without touching your other saved cards. A checksum-style validation runs when saved data is restored, so corrupted storage starts a clean sheet with a notice instead of showing invented rows.
Copy, CSV and printing
Copy summary places the lines, operators and totals on the clipboard as spreadsheet rows. Download CSV writes the same lines with a Result block, and Print produces a paper-friendly report with the totals. All three reflect the current on-screen state, including incomplete markers, so a reviewer can see whether the sheet was finished when it was exported.
Frequently asked questions
How do I add hours and minutes together?
Put each duration on its own line as hours and minutes and keep the plus operator. The total updates as you type, in H:MM, decimal hours and plain minutes. Blank lines are skipped, and a line that is half-typed is flagged rather than counted as zero.
Can the total go past 24 hours?
Yes. These are durations, not clock times, so 48:30 plus 2:45 shows 51:15. Nothing wraps at midnight because no clock is involved. Weekly totals, accrued leave and project time regularly exceed 24 hours.
What does a negative total mean?
A negative result such as -0:30 appears when the subtracted lines outweigh the added ones, for example 1:00 minus 1:30. It is a valid signed duration — usually a correction or an over-deduction — and the flagged source line shows where to look.
Is 1:30 the same as 1.3 hours?
No. 1:30 means one hour and thirty minutes, which is 1.50 decimal hours. Decimal 1.30 would be one hour and eighteen minutes. Use the converter on the page, which divides minutes by 60 instead of pasting the digits after the colon.
Why is my decimal entry rejected?
The converter and decimal display only describe whole minutes. A value such as 45.33 hours is 2,719.8 minutes, which cannot be represented exactly in this tool, so it is refused with the exact figure rather than rounded behind your back.
Where is my sheet saved?
In this browser’s local storage, under its own profile for this tool only. Reset clears it without affecting your saved cards on other calculators, and corrupted or unsupported storage starts an empty sheet with a notice instead of restoring invented rows.