Time Speed Distance Calculator — TSD Formula
Calculate time, speed, or distance using the TSD formula. Enter any two values to find the third. See also our Speed Calculator and Pace Calculator.
How to Use the TSD Formula
- Select what you want to calculate: speed, time, or distance.
- Enter the two known values.
- Click Calculate to find the unknown value.
- The TSD triangle helps remember: Distance = Speed x Time.
- Rearrange for any variable: Speed = D/T, Time = D/S.
Formula
Distance = Speed x Time
Speed = Distance / Time
Time = Distance / Speed
Example
Distance: 100 km, Time: 1h 40m (1.667 hours)
Speed = 100 / 1.667 = 60 km/h
Speed Conversion Reference
| km/h | mph | m/s |
|---|---|---|
| 10 | 6.21 | 2.78 |
| 30 | 18.64 | 8.33 |
| 60 | 37.28 | 16.67 |
| 100 | 62.14 | 27.78 |
| 120 | 74.56 | 33.33 |
Frequently Asked Questions
What is the TSD formula?
TSD stands for Time, Speed, Distance. The fundamental relationship is Distance = Speed x Time. Knowing any two values lets you calculate the third.
How do I convert km/h to m/s?
Divide by 3.6. For example, 72 km/h = 72/3.6 = 20 m/s.
What is average speed vs instantaneous speed?
Average speed is total distance divided by total time. Instantaneous speed is the speed at a specific moment (what your speedometer shows).
Does this account for acceleration?
No, this calculator assumes constant speed. For problems involving acceleration, you need kinematic equations (v = u + at, s = ut + 0.5at²).
How is this different from the pace calculator?
The pace calculator is designed for runners and shows pace in min/km or min/mile. This calculator works with any speed unit and is more general-purpose.