Time Calculator
Add or subtract multiple time durations — hours, minutes, and seconds — and get a running total instantly. Because time runs in base-60, not base-10, 45 minutes plus 30 minutes isn’t 75 minutes on a clock face, it’s 1 hour 15 minutes. This calculator carries that math for you automatically, including clean handling when a subtraction goes negative.
➕ Add or Subtract Time Durations
Enter up to 8 rows of hours, minutes, and seconds — flip a row’s sign to subtract it.
Overflow carries over automatically — 90 minutes becomes 1h 30m.
Result
2h 15m 0s
2 hours, 15 minutes, 0 seconds
2
Hours
15
Minutes
0
Seconds
2.25
Decimal Hrs
📐 Result in All Units
| Unit | Value |
|---|---|
| Seconds | 8,100 |
| Minutes | 135 |
| Hours | 2.25 |
| Days | 0.09375 |
| Weeks | 0.013393 |
| Milliseconds | 8,100,000 |
How Duration Addition Actually Works
Every entry you type — hours, minutes, seconds, and a +/− sign — first gets converted into a single signed number of total seconds. All those plain integers are then added together (or subtracted, when a row’s sign is negative), and only at the very end does the running total get converted back into hours, minutes, and seconds. Doing the carry-over at the very end, rather than column-by-column, is what avoids mistakes like “90 minutes” showing up as a final answer instead of the correct “1 hour 30 minutes.”
60
Seconds per Minute
60
Minutes per Hour
3,600
Seconds per Hour
1,000
Milliseconds per Second
🧮 The Conversion Formula
total_seconds = sign × (h×3600 + m×60 + s)sum = Σ total_seconds for every rowhours = ⌊|sum| ÷ 3600⌋, minutes = ⌊remainder ÷ 60⌋, seconds = remainderThe sign of the final sum is tracked separately from its magnitude, which is why a negative result — like subtracting a 2h 45m task from a 2h 00m budget — displays as a clean “-45m 0s” rather than an error or a wrapped-around clock time.
🎯 Where This Comes Up
- Task durations: add up several logged chunks of work into one total.
- Recipe timing: combine sequential prep, cook, and rest segments.
- Clip lengths: sum video or audio segments before editing them together.
- Interval training: total work and rest blocks against a session budget.
Need the span between two clock times instead of adding standalone durations? Try our hours calculator or, for a full weekly timesheet, the time card calculator.
📋
Task Durations
Stack up how long several separate tasks took — logged individually, then combined into one accurate project total.
🍳
Cooking & Recipes
Add sequential timer segments (marinate, prep, bake, rest) to see the total time a recipe actually needs, start to finish.
🎬
Video & Audio Clips
Sum multiple clip or track lengths before editing them together, or check how much runtime you have left against a target.
🏋️
Workout Intervals
Add up work and rest intervals to confirm a circuit or session fits inside a planned time budget.
— FAQ