Speed

Just how fast is Mach 3?

Air & orbit

Mach 3

1,029 m/smetres per second

3,704.4 km/hkilometres per hour

2,301.8 mphmiles per hour

3.4324 × 10⁻⁶ cspeed of light

Mach 33,704 km/hSpeed · definition

Lockheed SR-71 Blackbird3,528 km/hRepresentative cruise speed · specified · range 3,240 km/h–3,600 km/h

Each track shows distance covered in the same second. The small illustrations identify the movers; their sizes are schematic.

A little perspective

Mach 3 moves about 1.05 times as fast as Lockheed SR-71 Blackbird.

Measurements, assumptions & sources +

Mach 3

Mach depends on sound speed. Here Mach 1 is 343 m/s in dry air at 20 °C.

NIST — SI conversion factors

Lockheed SR-71 Blackbird

A rounded SR-71 reference: 32.7 m long, 16.9 m span, about 78 t maximum takeoff mass and roughly 980 m/s at high-speed cruise. Mission profile changes speed and mass.

NASA Armstrong — SR-71 Blackbird

The marked representative cruise speed is calibrated. Unmeasured illustration details are representative.

Measurement details

Why these numbers?

The visual compares speed with representative cruise speed. The records below preserve each value’s basis and caveats.

Mach 3

3,704 km/h

Speed · definition

Mach depends on sound speed. Here Mach 1 is 343 m/s in dry air at 20 °C.

Lockheed SR-71 Blackbird

3,528 km/h

Representative cruise speed · specified · range 3,240 km/h–3,600 km/h

A rounded SR-71 reference: 32.7 m long, 16.9 m span, about 78 t maximum takeoff mass and roughly 980 m/s at high-speed cruise. Mission profile changes speed and mass.

Comparing: Speed ↔ Representative cruise speed
Relative size: Mach 3 is larger on this measurement by a factor of about 1.05. Mach 3's selected measurement is approximately 5% greater than Lockheed SR-71 Blackbird's.