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. Change the inputs to update the chart or diagram.
Your inputs
Choose a preset or enter a distance. Presets are comparison references, not live routes. Results update as you edit.
Calculations run in your browser. Inputs are not saved or sent to analytics.
How it works
- One-way travel time = ÷ ; Round-trip duration = 2 × ÷
- Dry-air sound speed: a = √(1.4 × 287.05 × (T°C + 273.15)) m/s; Mach = ÷ 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
Input and formula key
Your result
Complete the inputs to see your result.
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/JPL — planetary mean orbital distances Sources reviewed: 2026-10-07
- NASA — Proxima Centauri b Sources reviewed: 2026-10-07
- NASA — Large Magellanic Cloud Sources reviewed: 2026-10-07
- NASA — Andromeda, nearest large galaxy Sources reviewed: 2026-10-07
- OurAirports — public-domain airport coordinates Sources reviewed: 2026-10-07
- NASA — mean lunar distance Sources reviewed: 2026-10-06
- NASA — sound speed in an ideal gas Sources reviewed: 2026-10-06
