Conversion
Time Duration Calculator
Add, subtract, or average multiple time durations. Get results in HH:MM:SS and decimal hours for timesheets and project tracking.
Enter time durations and click Calculate
How is this calculated?
Convert each entry to total seconds:
Total Seconds = Hours × 3600 + Minutes × 60 + Seconds
Sum: Add all total seconds together
Subtract: First entry seconds - sum of remaining
Average: Sum ÷ number of entries
Convert result back:
Hours = floor(Total ÷ 3600)
Minutes = floor((Total % 3600) ÷ 60)
Seconds = Total % 60
Decimal hours = Total Seconds ÷ 3600
Total minutes = Total Seconds ÷ 60FAQ
Frequently asked questions about time calculations
How do I add hours and minutes together?
Add hours separately, add minutes separately. If minutes exceed 60, carry over: 2h 45m + 1h 30m = 3h 75m = 4h 15m. Our calculator handles this automatically, including seconds overflow.
How do I convert hours and minutes to decimal?
Divide minutes by 60 and add to hours. Example: 2 hours 30 minutes = 2 + (30÷60) = 2.5 decimal hours. For seconds: 2h 30m 45s = 2 + (30÷60) + (45÷3600) = 2.5125 hours.
How do I calculate average time?
Add all durations together, then divide by the number of entries. Example: three tasks taking 1h 20m, 2h 10m, and 1h 45m = 5h 15m total ÷ 3 = 1h 45m average.
How do I subtract time durations?
Convert to total seconds, subtract, then convert back. If subtracting larger from smaller, borrow: 3h 15m - 1h 45m → 2h 75m - 1h 45m = 1h 30m. Our calculator handles borrowing automatically.
How many minutes are in a work day?
A standard 8-hour work day has 480 minutes (8 × 60). Including a 30-minute lunch: 450 productive minutes. A 40-hour work week = 2,400 minutes = 144,000 seconds.
How do I track time for timesheets?
Record start and end times, subtract to get duration per task. Sum all durations for daily/weekly totals. Use decimal hours for billing: 7.75 hours = 7 hours 45 minutes. Quarter-hour rounding is common in billing.