Speed Calculator
The speed, distance, and time relationship is fundamental to physics, travel planning, and engineering. Solve for any of the three variables with automatic unit conversion.
Speed, Distance, Time
Three Core Formulas
v = d/t (speed = distance ÷ time). d = v × t (distance = speed × time). t = d/v (time = distance ÷ speed). SI units: speed in m/s, distance in metres, time in seconds. Any consistent unit set works.
Speed vs Velocity
Speed is a scalar (magnitude only). Velocity is a vector (magnitude and direction). A car going around a circular track at a constant 60 km/h has constant speed but constantly changing velocity. This distinction matters in physics but not for most practical calculations.
Reference Speeds
Average walking: 1.4 m/s (5 km/h). Cycling: 4–8 m/s. Sprint world record: 12.4 m/s. Sound in air: 343 m/s. Passenger aircraft: ~250 m/s. Speed of light: 299,792,458 m/s.
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