Durations use a mixed base (60 seconds, 60 minutes, 24 hours), so adding them by hand needs carrying at each step. Converting both to seconds, adding, then splitting back avoids errors.
How to use the Time Calculator: Add and Subtract Durations
- Duration 1: days
- Duration 1: hours
- Duration 1: minutes
- Duration 1: seconds
- Operation
- Duration 2: days
- Duration 2: hours
- Duration 2: minutes
- Duration 2: seconds
Results update as you type, and every field accepts the units shown in its menu.
How it works
Enter the two durations and choose add or subtract.
Inputs explained
| Field | What to enter |
|---|---|
| Duration 1: days | A number |
| Duration 1: hours | A number |
| Duration 1: minutes | A number |
| Duration 1: seconds | A number |
| Operation | Choose one: Add (+), Subtract (−) |
| Duration 2: days | A number |
| Duration 2: hours | A number |
| Duration 2: minutes | A number |
| Duration 2: seconds | A number |
What each result means
- Total seconds = ([Duration 1: days]×86400 + [Duration 1: hours]×3600 + [Duration 1: minutes]×60 + [Duration 1: seconds]) + [Operation]×([Duration 2: days]×86400 + [Duration 2: hours]×3600 + [Duration 2: minutes]×60 + [Duration 2: seconds])
- Days = sign([Total seconds])×floor([Absolute seconds]÷86400)
- Hours = sign([Total seconds])×floor(mod([Absolute seconds], 86400)÷3600)
- Minutes = sign([Total seconds])×floor(mod([Absolute seconds], 3600)÷60)
- Seconds = sign([Total seconds])×mod([Absolute seconds], 60)
- Total hours = [Total seconds]÷3600
- Total minutes = [Total seconds]÷60
Example values
How the main result changes when Duration 1: days changes and everything else stays at the example values above:
| Duration 1: days | Days |
|---|---|
| 0.5 | 1 |
| 0.75 | 1 |
| 1 | 2 |
| 1.25 | 2 |
| 1.5 | 2 |
| 2 | 3 |
Formula
Total seconds = (d₁ × 86,400 + h₁ × 3,600 + m₁ × 60 + s₁) ± (d₂ × 86,400 + h₂ × 3,600 + m₂ × 60 + s₂)
Then split back into days, hours, minutes and seconds
Worked example
Inputs: Duration 1 – days: 1; Duration 1 – hours: 14; Duration 1 – minutes: 35; Duration 1 – seconds: 50; Operation: Add (+); Duration 2 – days: 0; Duration 2 – hours: 10; Duration 2 – minutes: 40; Duration 2 – seconds: 25.
Results: Total seconds = 177,375; Days = 2; Hours = 1; Minutes = 16; Seconds = 15; Total hours = 49.271; Total minutes = 2,956.25.
Frequently asked questions
How do I add times together?
Add seconds, minutes, hours and days separately, carrying 60 seconds to a minute, 60 minutes to an hour and 24 hours to a day.
What is 1 d 14:35:50 + 10:40:25?
2 days 1 h 16 min 15 s.
How many seconds in a day?
86,400.