About the Relative Speed Calculator
Relative speed of two objects moving towards each other or in the same direction, and closing time.
Also known as: closing speed, relative velocity, approach speed.
How to use this calculator
- Enter speed of object 1, speed of object 2, direction, distance apart.
- The result updates instantly as you type — press Calculate (or Enter) at any time.
- Review the breakdown shown under the main result.
- Use Copy result or Share to save the answer or send a link with your inputs.
Formula
Towards: v₁ + v₂ · Same direction: |v₁ − v₂|
Worked example
Using the values pre-filled in the calculator above:
- Speed of object 1 = 60
- Speed of object 2 = 40
- Direction: Towards each other
- Distance apart = 200
the calculator returns:
- Relative speed: 100
- Time to meet: 2 hours (120 min)
- Gap change per hour: 100