Practical tools for measured work
Mach and speed of sound calculator
Convert Mach and airspeed at an explicit temperature, including mph, km/h, ft/s and knots.
Calculate the layout, check the diagram, then print the result for the shop or jobsite.
Mach comparison at entered temperature
| Mach number | m/s | km/h | mph |
|---|---|---|---|
| 0.5 | 170.146143 | 612.526116 | 380.606083 |
| 1 | 340.292287 | 1225.05223 | 761.212166 |
| 2 | 680.584574 | 2450.10447 | 1522.42433 |
| 3 | 1020.87686 | 3675.1567 | 2283.6365 |
| 5 | 1701.46143 | 6125.26116 | 3806.06083 |
| 10 | 3402.92287 | 12250.5223 | 7612.12166 |
| 20 | 6805.84574 | 24501.0447 | 15224.2433 |
How it works
Mach number is airspeed divided by the local speed of sound. For dry ideal air, sound speed = √(1.4 × 287.05 × absolute temperature). At 15°C, Mach 1 is approximately 340.29 m/s or 761.21 mph; at 20°C it is about 343.23 m/s. It is not one fixed speed for every atmosphere.
Current-input example
The result above uses these exact values. This snapshot is included when the page is printed so the output can be checked against the original measurements.
- Known speed measure
- Mach number
- Mach number
- 1
- Local air temperature
- 15 °C
Primary result: Local speed of sound: 340.292287 m/s.
Before using the result
- Check the selected mode, units and input values before using the result.
- Read the assumptions and rounding rules; compare the worked example with your intended calculation.
- A numerical result does not supply missing context or change the stated limitations.
Limitations
Temperature is restricted to −100–100°C. Use speed relative to the surrounding air, not ground speed. This dry-air model excludes humidity corrections, other gases and high-temperature chemistry. Large Mach entries are numerical conversions at the supplied ambient conditions, not a prediction of vehicle performance.
Frequently asked questions
What should I verify before using this result?
Check the input values, units, dates and assumptions. Compare the method and its stated limits with the source relevant to your task.
Why might the finished result differ?
Results depend on the entered data and the model’s assumptions. Rounding, changing conditions or omitted factors can affect the comparison. Read the limitations before using the result.
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