Convert Meters per Second to Mach - Speed Converter
This converter translates a speed given in meters per second (m/s) into a Mach number (ratio of object speed to local speed of sound). Mach number is dimensionless and commonly used in aeronautics, acoustics, and fluid dynamics to classify subsonic, transonic, supersonic, and hypersonic regimes.
Because the local speed of sound depends on the thermodynamic state of the medium (principally temperature for gases), a single numeric conversion requires an assumption about atmospheric conditions. This tool uses a standard reference for air unless otherwise stated in the methodology and provides guidance on accuracy and when to use measured local speed of sound instead.
Interactive Converter
Convert between meter per second and mach with precision rounding.
Quick reference table
| Meter per Second | Mach |
|---|---|
| 1 m/s | 0.0105 M |
| 5 m/s | 0.0525 M |
| 10 m/s | 0.105 M |
| 25 m/s | 0.2624 M |
| 50 m/s | 0.5248 M |
| 100 m/s | 1.0496 M |
Methodology
Primary relationship: Mach number M is defined as M = v / a where v is object speed and a is the local speed of sound in the same medium and direction.
For dry air under typical engineering assumptions, the speed of sound is estimated from the ideal-gas relation a = sqrt(gamma * R_specific * T), where gamma is the ratio of specific heats, R_specific is the specific gas constant for air, and T is absolute temperature (Kelvin). This converter assumes gamma = 1.4 and R_specific = 287.058 J/(kg·K) unless a different reference is specified in accompanying documentation.
A standard reference temperature commonly used for conversions is 15 °C (288.15 K). At that temperature the speed of sound in air is approximately 340.294 m/s, so 340.294 m/s corresponds to Mach 1 under those reference conditions. For precise or regulatory work, use measured local temperature and humidity or direct measurement of speed of sound; references to NIST and ISO standards are provided below.
Worked examples
Example 1: 170.147 m/s with default reference speed of sound 340.294 m/s → Mach = 170.147 / 340.294 ≈ 0.5.
Example 2: 340.294 m/s at reference conditions → Mach = 340.294 / 340.294 = 1.0.
Example 3: 1020.882 m/s at reference conditions → Mach = 1020.882 / 340.294 ≈ 3.0.
Key takeaways
This converter computes Mach as the ratio of input speed to an assumed local speed of sound. Default reference uses standard air at 15 °C (a ≈ 340.294 m/s).
For engineering, safety, or regulatory purposes, replace the default with measured local conditions and document assumptions and uncertainties in accordance with NIST and applicable ISO/IEEE guidance.
Further resources
Expert Q&A
Does Mach depend on temperature and altitude?
Yes. The local speed of sound depends primarily on temperature (and to a lesser extent on composition and humidity). Altitude affects temperature and pressure through the atmosphere profile, so Mach for a given m/s value will change with altitude. Use local thermodynamic data for accurate results.
Can I use this conversion for gases other than air?
The standard assumptions and numeric reference (gamma = 1.4, R = 287.058 J/(kg·K)) apply to dry air. For other gases, use the appropriate specific heat ratio and gas constant or measure the speed of sound directly before converting.
How accurate is the conversion?
Using the standard reference (15 °C, dry air) gives typical engineering accuracy for many applications, but not for high-precision metrology or regulatory compliance. Uncertainty arises from temperature variability, humidity, and non-ideal gas effects. For precision work, measure or calculate the local speed of sound using traceable sensors and follow NIST and ISO guidance.
Is Mach calculated from true airspeed or indicated/ground speed?
Mach is defined using the speed relative to the local air (true airspeed for aircraft). Ground speed differs from true airspeed when there is wind. For aerodynamic/regulatory use, convert true airspeed to Mach using local speed of sound.
Are there operational limits where this conversion is not appropriate?
Yes. In transonic and supersonic regimes compressibility effects, shock formation, and non-equilibrium thermodynamics mean local flow properties can differ significantly from free-stream approximations. For high-Mach applications consult aerodynamic specialists and relevant standards before using a simple conversion.
How should I report converted values for engineering or regulatory documents?
Report the input speed, the assumed or measured local speed of sound (including temperature and humidity or reference condition), the computed Mach value, and an uncertainty estimate. Cite applicable standards such as NIST and ISO where measurement traceability is required.
Sources & citations
- NIST — Reference on Constants, Units, and Uncertainty — https://www.nist.gov
- ISO — Standard atmosphere and related measurement practices (see ISO standards catalogue) — https://www.iso.org
- IEEE — Recommended practices for measurement and reporting in instrumentation and controls — https://standards.ieee.org
- OSHA — Guidance on measurement practices and workplace safety for compressed gases and high-speed machinery — https://www.osha.gov