Time Calculator
Add or subtract two durations in hours, minutes and seconds. Handy for total times, splits and time math.
Minutes and seconds may be 60 or more; they are automatically carried into higher units and the result is normalized.
| Row | Entered h:m:s | Decimal h |
|---|
Work shifts? Hours calculator · lap timing: Stopwatch · time zones: Time zone converter.
How to use
Enter two or more durations, choose add or subtract, and see the result in h:m:s plus decimal hours for payroll. Export a CSV breakdown.
This calculator adds or subtracts durations (hours : minutes : seconds), normalizes the result, and shows decimal hours. Type each duration in its own row, pick + or −, and read the result instantly — 1:30:00 + 0:45:00 = 2:15:00, which is 2.25 decimal hours for payroll or invoicing.
Durations are base-60: 60 seconds carry into 1 minute, 60 minutes into 1 hour (the sexagesimal system inherited from Babylonian timekeeping). You can safely type 90 in the minutes field — it normalizes to 1 h 30 m instead of rejecting the input. Decimal hours are the industry convention for timesheets: minutes ÷ 60, so 15 minutes = 0.25 h and 100 minutes = 1.667 h (not 1.40).
Boundaries worth knowing: this tool works with durations (lengths of time), not clock times — for shift start/end times use the Hours Calculator instead. Subtracting a longer duration from a shorter one gives an honest negative result (−2:30:00), not an error. Results that exceed 24 hours roll into days (20:00:00 + 8:00:00 = 1 d 04:00:00). Payroll rounding policies (e.g. nearest quarter-hour) vary by employer and jurisdiction — this tool reports exact values and leaves rounding decisions to you.
Worked example — freelance invoice: Monday 3:25:00, Tuesday 2:50:00, Wednesday 4:05:00. Add the three rows: 10:20:00 total = 10.333 decimal hours; at $45/hour that is $465.00. The CSV export reproduces the per-row breakdown so the numbers on your invoice can be audited line by line.
Published test vectors — each validated against the live tool: 1:30:00 + 0:45:00 = 2:15:00 (2.25 h) · 90 minutes input normalizes to 1:30:00 · 5:00:00 − 7:30:00 = −2:30:00 · 20:00:00 + 8:00:00 = 1 d 04:00:00 · 0:59:59 + 0:00:01 = 1:00:00 (double carry). Last verified: 2026-08-12.
FAQ
How do I convert minutes to decimal hours for payroll?
Divide minutes by 60. 15 min = 0.25 h, 30 min = 0.50 h, 45 min = 0.75 h, 100 min = 1.667 h. The common payroll mistake is writing 1 h 40 m as 1.40 instead of 1.667 — this calculator shows the correct decimal automatically.
Can I add more than two durations at once?
Yes. Click “+ Add duration row” for each extra block of time (e.g. one row per work day). Add mode sums every row; subtract mode takes the first row and subtracts all the others from it.
What happens when minutes or seconds are 60 or more?
They carry into the next unit automatically, exactly like base-60 arithmetic: 90 minutes becomes 1 h 30 m, and 0:59:59 + 0:00:01 becomes exactly 1:00:00. You never need to pre-convert your inputs.
Why did I get a negative time, and what does it mean?
Subtracting a longer duration from a shorter one yields a negative duration such as −2:30:00. It means the second block of time exceeds the first by that amount — useful for “how far am I over budget” checks. It is deliberate, not an error.
Is this the right tool for shift start and end times?
No — this tool handles durations (amounts of time). If you have clock times like “09:00 to 17:30 minus a 30-minute break”, use the Hours Calculator, which also handles overnight shifts and pay estimates.
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