Speed Calculator
Adjust the inputs below. Results update as you type.
How it works
Speed = distance / time. Distance = speed × time. Time = distance / speed. Convert units: 1 mph = 1.609 km/h = 0.447 m/s = 0.868 knots. Average speed = total distance / total time (not average of speeds). The harmonic mean applies for equal-distance legs at different speeds. Escape velocity from Earth: 11.2 km/s. Speed of light: 299,792 km/s.
Input guidance
- Confirm date/time/unit settings before comparing outputs.
- If a task has optional fields, run both with and without them to understand impact.
- Save scenario variants when making practical decisions.
The formula
Speed = distance ÷ time. Rearranged, distance = speed × time and time = distance ÷ speed. Keep units consistent for a correct result.
Worked example
Covering 150 miles in 2.5 hours is a speed of 150 ÷ 2.5 = 60 mph.
More examples to test
- Quick-pass example: run default assumptions for a first estimate.
- Refined example: update one assumption at a time to isolate impact.
How to interpret results
Use outputs as operational estimates and pair them with local constraints, business rules, or provider requirements.
When this can be inaccurate
Utilities can miss local policy details, special-case rules, and environment-specific constraints.
Change history
- July 2026: Quality-reviewed for publication with formula checks and explanatory copy updates.
Site-wide corrections also appear on the corrections log.
Find productivity tools for everyday workflows
General recommendation, not professional advice.
Frequently asked questions
How do I calculate average speed?+
Divide total distance by total time. Note this differs from averaging speeds if the legs take different amounts of time.
How do I convert mph to km/h?+
Multiply mph by 1.60934. 60 mph is about 96.6 km/h.
What is the difference between speed and velocity?+
Speed is how fast you move; velocity adds direction. Two cars at 50 mph in opposite directions have the same speed but different velocities.
Why are outputs slightly different from another tool?+
Different tools can use different rounding rules, default assumptions, and treatment of edge cases.
How can I improve estimate reliability?+
Use verified inputs from real records and re-run calculations after major assumption changes.