Calculate Speed of Sound in Air at 20 Degrees Celsius

Understanding the speed of sound in air is fundamental to physics, acoustics, and engineering. This calculator precisely computes the speed of sound at 20°C (68°F) using the ideal gas law and standard atmospheric conditions.

What is the speed of sound?

The speed of sound refers to how fast sound waves travel through a medium, typically air. At 20°C (68°F), sound travels at approximately 343 meters per second (m/s) or 1,125 feet per second (ft/s).

Sound speed varies with temperature, humidity, and air pressure. This calculator uses standard conditions to provide an accurate baseline measurement.

Formula for speed of sound

The speed of sound in air (v) can be calculated using the following formula:

v = 331.3 + (0.6 × T)

Where:

v = speed of sound in meters per second (m/s)
T = temperature in degrees Celsius (°C)

This formula is derived from the ideal gas law and accounts for the relationship between temperature and the speed of sound waves through air.

Assumptions and limitations

This calculator makes the following assumptions:

Standard atmospheric pressure (101.325 kPa)
Dry air with no moisture content
No wind or other air movement affecting the measurement

Note: Actual conditions may vary slightly due to humidity, altitude, and other environmental factors. This calculator provides an approximation for standard conditions.

Worked example

Let's calculate the speed of sound at exactly 20°C:

Identify the temperature: T = 20°C
Plug into the formula: v = 331.3 + (0.6 × 20)
Calculate: v = 331.3 + 12 = 343.3 m/s

The result shows sound travels at approximately 343.3 meters per second at 20°C.

Practical applications

Knowing the speed of sound has several practical uses:

Acoustic engineering and room design
Weather forecasting and storm tracking
Sonar and underwater acoustics
Medical imaging and diagnostics
Sports performance analysis

Understanding these applications helps professionals make informed decisions in their respective fields.

Frequently Asked Questions

What is the speed of sound at 20°C?

The speed of sound at 20°C (68°F) is approximately 343 meters per second (m/s) or 1,125 feet per second (ft/s).

Does humidity affect the speed of sound?

Yes, humidity can slightly increase the speed of sound in air. However, this calculator uses standard dry air conditions.

How does temperature affect sound speed?

The speed of sound increases by about 0.6 m/s for every 1°C increase in temperature at standard conditions.

What is the speed of sound in other units?

At 20°C, the speed of sound is approximately 1,125 feet per second (ft/s) or 761 miles per hour (mph).

Can sound travel faster than this?

Yes, sound travels faster in solids and liquids than in air. For example, sound travels at about 5,120 m/s in steel.