Time Calculator
Add and subtract multiple time values together.
Total Time
What is a Time Calculator?
A time calculator adds and subtracts durations written in days, hours, minutes, and seconds. Instead of juggling 60-second minutes and 24-hour days in your head, you enter each interval on its own row, mark it with a plus or minus, and get one clean total.
It is useful anywhere durations pile up: totaling a weekly timesheet, summing training splits, checking the length of a multi-segment video, or netting driving time against rest breaks. The result appears four ways — as days:hours:minutes:seconds and as straight totals in hours, minutes, and seconds — so you can quote it in whichever unit you need.
Every entry is converted to seconds before being combined, so overflow handles itself: 90 minutes equals 1 hour 30 minutes, and a 30-hour total rolls over into 1 day 6 hours.
How the Calculation Works
Each row becomes a single count of seconds, signed by its Operation selector, and added to the running total:
Row Seconds = Days × 86,400 + Hours × 3,600 + Minutes × 60 + Seconds
Total = Row 1 Seconds ± Row 2 Seconds ± ... ± Row N Seconds
The signed total is then divided back down by 86,400, 3,600, and 60 to recover days, hours, minutes, and seconds.
- Operation — the + or − dropdown on each row. Plus adds the interval; minus subtracts it.
- Days — whole 24-hour days. Each day contributes 86,400 seconds.
- Hours — the hours part of the interval, 0-23. Each hour is 3,600 seconds.
- Minutes — the minutes part of the interval, 0-59.
- Seconds — the seconds part of the interval, 0-59.
Worked Example: Totaling a Weekly Timesheet
Suppose you worked five shifts — Monday 8:15, Tuesday 7:45, Wednesday 8:30, Thursday 8:05, Friday 7:25 (hours:minutes). Enter each as a plus row with the Hours and Minutes fields and click Calculate Total. Each row first becomes seconds:
- Monday: 8 × 3,600 + 15 × 60 = 28,800 + 900 = 29,700 seconds
- Tuesday: 7 × 3,600 + 45 × 60 = 25,200 + 2,700 = 27,900 seconds
- Wednesday: 8 × 3,600 + 30 × 60 = 28,800 + 1,800 = 30,600 seconds
- Thursday: 8 × 3,600 + 5 × 60 = 28,800 + 300 = 29,100 seconds
- Friday: 7 × 3,600 + 25 × 60 = 25,200 + 1,500 = 26,700 seconds
Adding the five rows gives 29,700 + 27,900 + 30,600 + 29,100 + 26,700 = 144,000 seconds. Converting back, 144,000 − 86,400 = 57,600 seconds past one day, and 57,600 ÷ 3,600 = exactly 16 hours, so the total reads 1:16:00:00. The other lines show 40.00 total hours, 2,400.00 total minutes, and 144,000 total seconds.
Now deduct an unpaid 45-minute lunch each day. Five lunches total 5 × 45 = 225 minutes, or 3 hours 45 minutes, which is 3 × 3,600 + 45 × 60 = 10,800 + 2,700 = 13,500 seconds. A minus row of 3 hours 45 minutes makes the new total 144,000 − 13,500 = 130,500 seconds, which normalizes to 1:12:15:00. Check the decimal readout: 12 + 15 ÷ 60 = 12.25, plus the 24 hours in one day gives 36.25 total hours, and 2,175.00 total minutes multiplies back to 2,175 × 60 = 130,500 seconds.
Time Unit Conversions
These equivalents are handy for mental math and for sanity-checking a result:
| Duration | Hours | Minutes | Seconds |
|---|---|---|---|
| 1 hour | 1 | 60 | 3,600 |
| 8-hour workday | 8 | 480 | 28,800 |
| 1 day | 24 | 1,440 | 86,400 |
| 1 week | 168 | 10,080 | 604,800 |
How to Use
- On the first row, choose + or − from the Operation dropdown.
- Enter the Days, Hours, Minutes, and Seconds for that interval (the Hours field takes 0-23; Minutes and Seconds take 0-59).
- Click + Add Row for each additional interval and fill it in; use - Remove Row to delete the last row.
- Click Calculate Total.
- Read the result as days:hours:minutes:seconds, or use the Total Hours, Total Minutes, and Total Seconds lines for a single-unit figure.
Frequently Asked Questions
Can I subtract time?
Yes. Set any row's Operation dropdown to minus and that interval is subtracted from the total. In the worked example, one minus row of 3 hours 45 minutes removes the week's lunches, dropping the total from 144,000 to 130,500 seconds.
Is there a limit to rows?
No. Click + Add Row as many times as you need; each row gets its own operation selector and day, hour, minute, and second fields. The Remove Row button deletes the last row but always leaves at least one.
Does it handle overflow?
Yes. Every entry is converted to seconds first, so 90 minutes is treated exactly like 1 hour 30 minutes; on the way back, 60 seconds roll into a minute, 60 minutes into an hour, and 24 hours into a day.
Can the total be negative?
Yes. If you subtract more time than you add, the signed total drops below zero, and the days:hours:minutes:seconds figure and the total hours, minutes, and seconds are each prefixed with a minus sign.
How do I convert the result to decimal hours?
Read the Total Hours result line, which shows the decimal value rounded to two places. To convert by hand, divide the leftover minutes by 60 and the leftover seconds by 3,600, then add the whole hours plus 24 per day: 1:12:15:00 becomes 24 + 12 + 15/60 = 36.25 hours.
What is the difference between this and the Date Calculator?
This tool works with durations — spans of hours, minutes, and seconds — regardless of when they occur. BestCalc's Date Calculator works with calendar dates, adding or subtracting days, weeks, months, or years from a specific date.
Can I use this for a weekly timesheet?
Yes. Add one plus row per shift with the Hours and Minutes fields, then minus rows for unpaid breaks. Click Calculate Total and read the Total Hours line for payroll-style decimals — the example above turns five shifts and lunches into 36.25 paid hours.