Time Calculator
Add and subtract lengths of time in days, hours, minutes, and seconds, apply time to a date, or type the whole thing as one expression.
Empty fields count as zero. Carrying happens at 60 seconds, 60 minutes, and 24 hours.
Your total will appear here
Enter time values or an expression, then calculate to see the sum in days, hours, minutes, and seconds.
Which time tool should you use?
- Trying to measure the difference between two clock times? Use the Time Duration Calculator.
- Working with calendar dates? Use the Date Calculator.
Quick Answer
This is time arithmetic. It adds and subtracts spans of time in days, hours, minutes, and seconds, carrying at 60 and 24, and it can apply a span to a date and time. It does not measure the gap between two clock readings — that is what the Time Duration Calculator is for.
How It Works: Formula & Variables
Total = Σ (± values) · carry at 60s → 1m, 60m → 1h, 24h → 1d
- 1 day
- 24 hours · 1,440 minutes · 86,400 seconds.
- 1 hour
- 60 minutes · 3,600 seconds.
- 1 minute
- 60 seconds.
Values are added from the smallest unit up, carrying whenever a unit overflows.
Worked Examples
Example 1: Adding with a carry
1d 2h 3m 4s plus 4h 5s. Seconds give 9, minutes 3, hours 2 + 4 = 6, days 1. The total is 1 day, 6 hours, 3 minutes, 9 seconds.
Example 2: Subtracting with a borrow
1 hour 5 minutes minus 40 minutes. Since 5 minutes is less than 40, the tool borrows an hour (60 minutes): 65 − 40 = 25, and the hours drop to zero. The answer is 25 minutes.
Key Concepts
Time carries at 60, not 100: 1:30 plus 1:30 is 3:00, not 2:60. Minutes and seconds roll over at 60, which is the part manual math tends to get wrong.
Adding is not the same as measuring: This tool combines lengths of time. Finding how long sits between 9:34 and 11:03 is a duration question, handled by a different tool.
Blank fields mean zero: An empty box is treated as nothing to add, so you only fill in the units you actually have.
Common Mistakes
Adding time as if it were decimal: 1:30 plus 1:30 rolls over at 60, giving 3:00 rather than 2:60.
Confusing this with a duration tool: This calculator adds and subtracts spans; it does not read the gap between two clock times.
Misreading blank fields: An empty box counts as zero, not as "leave this part out of the math".
Frequently Asked Questions
Enter each length of time in the day, hour, minute, and second fields and the calculator adds them with proper carrying — 60 seconds roll into a minute, 60 minutes into an hour, and 24 hours into a day. Rows you leave blank simply count as zero.
Yes. Set a row to the minus sign and the calculator borrows across units where it needs to, so 1 hour 5 minutes minus 40 minutes correctly gives 25 minutes rather than a negative-looking result.
The "Add to date" tab takes a starting date and time, then adds or subtracts a span in days, hours, minutes, and seconds to give you a new date and time.
This tool adds and subtracts lengths of time, such as 2 hours plus 3 hours. It does not measure the gap between two clock readings — for that, use the Time Duration Calculator.
You can type a whole calculation in one line using values with d, h, m, or s joined by plus and minus signs, for example 1d 2h 3m 4s + 4h 5s − 2030s. The calculator reads it and returns the total.
There are 86,400 seconds in a day, which is 24 hours multiplied by 3,600 seconds per hour.
Related Calculators
Time Duration Calculator
Measure the difference between two clock times instead of adding up lengths of time.
Date Calculator
Work with calendar dates — the gap between two, or adding days, weeks, months, and years.
Hours Calculator
Turn a start and end time into hours worked, with break deduction and decimal hours.
Time Card Calculator
Add up a full week of in and out times, overtime, and gross pay.