Speed Distance Time.
Select which variable to solve for — Speed, Distance, or Time — then enter the other two values with your choice of units. Results update instantly with automatic unit conversion.
Multi-Unit Support
Speed: mph, km/h, m/s. Distance: miles, km, meters, feet. Time: hours, minutes, seconds. All conversions are handled internally — enter your values in familiar units and get the result in your preferred unit without manual conversion.
Solve for Any Variable
Select which variable to calculate and the corresponding input field is disabled. The two known values feed into the formula and the unknown is solved. Useful for trip planning, physics problems, running pace, and aviation calculations.
Speed, Distance, Time Calculation Methodology.
The Calculation Branch
Industrial Standards.
All inputs are converted to SI base units internally (meters per second for speed, meters for distance, seconds for time). The calculation is performed in SI units, then the result is converted back to the selected output unit. This approach eliminates unit-mismatch errors and ensures accuracy across all unit combinations.
In-Depth Analysis & Reference Data
Practical applications: (1) Road trip planning — enter distance and speed limit to find travel time. (2) Running/cycling pace — enter distance and target time to find required speed. (3) Aviation — calculate fuel burn rate requiring precise time-at-speed. (4) Physics homework — standard kinematics problems. (5) Shipping logistics — estimate transit time based on vessel speed and nautical miles. (6) Sound and light speed problems — enter speed of sound (340 m/s) or light (3×10⁸ m/s) to find travel times.
Registry Questions & FAQ.
How do I calculate average speed for a multi-leg journey?
Average speed = Total Distance ÷ Total Time. Do NOT average the speeds of each leg — this gives the wrong answer. If you drove 60 mph for 2 hours (120 miles) then 90 mph for 1 hour (90 miles), total is 210 miles in 3 hours = 70 mph average. Not (60+90)/2 = 75 mph.
How does this handle acceleration?
It doesn't — this calculator assumes constant speed. For problems with acceleration, use the kinematic equations: v = u + at, s = ut + ½at², v² = u² + 2as. Constant-speed calculations are appropriate for most practical journey planning but not for analyzing vehicle acceleration or ballistic trajectories.
All metrics verified against ISO/ASTM benchmarks.