Mach (20°C, 1 atm) to Kilometer per Minute

Mach number is the ratio of an object's speed to the speed of sound in the surrounding medium. Mach 1 at 20°C, 1 atm equals approximately 343.6 m/s (1,235 km/h).

Mach = velocity ÷ speed_of_sound. At 20°C: Mach 1 = 343.6 m/s. Speed of sound = √(γRT/M) where γ = heat capacity ratio.

To m/s (at 20°C): × 343.6. To km/h (at 20°C): × 1,237. Note: changes with altitude and temperature.

Fighter jets (Mach 1.5–2.5), commercial aircraft (Mach 0.8–0.85), space shuttle reentry (Mach 25), and missile speeds.

Concorde: Mach 2.04. SR-71 Blackbird: Mach 3.3. X-15: Mach 6.7. Meteorites enter at Mach 50+. Subsonic <1, supersonic >1, hypersonic >5.

Thinking Mach is constant — it varies with temperature/altitude. At 30,000 ft, Mach 1 ≈ 295 m/s (colder air = slower sound).

Mach 1 = speed of sound. Below Mach 1 = subsonic. Mach 1–5 = supersonic. Above Mach 5 = hypersonic. It's a ratio, not a fixed speed.

Kilometer per minute measures how many kilometers are traveled in one minute. It's a less common but useful speed unit for high-speed contexts.

1 km/min = 60 km/h = 16.667 m/s. There are 60 minutes in an hour.

To km/h: × 60. To m/s: × 16.667. To mph: × 37.28.

Describing meteor speeds, high-speed rail in casual conversation, or military projectile velocities.

Earth's orbital speed: 1,800 km/min. Escape velocity: 40 km/min. Fastest manned aircraft (X-15): 6.7 km/min.

Confusing with km/h — 1 km/min is 60 times faster than 1 km/h, not the same.

Easy conversion: km/min × 60 = km/h. Example: 2 km/min = 120 km/h. Useful for mental math with fast speeds.