Travel time: speed, sound and light
Compare a journey at everyday speeds, the speed of sound and the speed of light, with custom distances and speeds.
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How it works
- One-way travel time = d ÷ v; Round-trip duration = 2 × d ÷ v
- Dry-air sound speed: a = √(1.4 × 287.05 × (T°C + 273.15)) m/s; Mach = v ÷ a
- c = 299,792,458 m/s; 1 AU = 149,597,870,700 m; 1 mi = 1,609.344 m
- References: NYC–LA 3,940 km (illustrative); Earth–Moon 384,400 km (mean); Sun–Earth 1 AU; one light-year = c × 31,557,600 seconds.
- Worked example: 3,940 km ÷ 100 km/h = 39.4 h
Assumptions and limitations
Speeds are constant; walking, driving and aircraft use illustrative 5, 100 and 900 km/h. Sound uses ideal dry air with γ = 1.4 and R = 287.05 J/(kg·K), between −50 and 50°C; humidity and wind are excluded. Space sound times assume an imaginary air-filled path, not propagation in a vacuum. Light uses vacuum c. No routing, stops, acceleration or relativity. Arrivals use UTC; years are 365.25 days. A round trip doubles the same distance and speed.
Sources
- NASA — speed of light and astronomical units Sources reviewed: 2026-10-06
- NASA — mean lunar distance Sources reviewed: 2026-10-06
- NASA — sound speed in an ideal gas Sources reviewed: 2026-10-06
