Instantly estimate sound speed in realistic air conditions. Switch methods, units, and environmental inputs quickly. Use the results to tune experiments and designs safely.
This calculator supports three common models. Choose the one that matches your inputs and required accuracy.
For the humid-air model, water vapor pressure is estimated from relative humidity:
| Temperature (°C) | Pressure (kPa) | RH (%) | Model | Speed (m/s) |
|---|---|---|---|---|
| 20 | 101.325 | 50 | Humid air | ≈ 343 |
| 0 | 101.325 | 0 | Dry air | ≈ 331 |
| 30 | 90 | 70 | Humid air | ≈ 349 |
| -10 | 101.325 | 40 | Temperature-only | ≈ 325 |
Values are rounded and shown for guidance only.
The speed of sound in air depends mainly on temperature, and it shifts with humidity and the local air state. This tool computes sound speed in m/s, km/h, mph, and ft/s using three selectable models. At 20 °C near sea level, sound travels close to 343 m/s, a common reference for room conditions.
Temperature sets the energy of molecular motion and dominates the outcome. Pressure becomes important when you use the humid-air model, because it helps determine density. Relative humidity changes the water vapor fraction, which alters density and therefore the calculated sound speed.
A practical rule is about 0.6 m/s increase per 1 °C rise around ordinary conditions. For example, moving from 0 °C to 30 °C can raise sound speed by roughly 18 m/s. This matters in time‑of‑flight ranging, Doppler measurements, and echo timing where milliseconds count.
For dry air, sound speed depends primarily on temperature, so pressure changes alone have limited effect. In the humid‑air approach, pressure affects density and helps keep results realistic when conditions are far from standard. If you enable altitude estimation, the calculator uses a standard atmosphere relationship up to 11,000 m.
Humid air can slightly increase sound speed because water vapor reduces the average molecular mass of the mixture. The calculator estimates vapor pressure from relative humidity and saturation pressure at the given temperature. In everyday ranges, the shift is small but measurable in acoustic calibration and environmental monitoring.
Use the humid‑air model when you have pressure and humidity data and want the most complete estimate. Choose dry air for controlled lab conditions or when humidity is negligible. Gamma is typically near 1.40 for air; adjusting it can explore sensitivity for different gas behavior assumptions.
Accurate sound speed supports HVAC duct acoustics, ultrasonic sensors, and speaker system alignment. It also improves outdoor experiments where temperature and humidity swing during the day. In aviation training, relating temperature, pressure, and altitude to sound speed helps interpret Mach and propagation effects.
Compare units to match your workflow: m/s for physics, km/h for transport contexts, mph for field notes, and ft/s for some engineering references. Exported CSV and PDF reports capture both inputs and outputs so you can document conditions, reproduce calculations, and share consistent results across teams.
Use the humid-air model when you know pressure and relative humidity. Use dry air for low-humidity labs. Use the temperature-only option for quick estimates when you only have temperature.
Higher temperature increases molecular motion, making pressure waves propagate faster. Around typical conditions, sound speed rises by about 0.6 m/s per 1 °C, which is noticeable in timing and ranging.
Not by itself for ideal dry air at fixed temperature. Sound speed mainly follows temperature. In the humid-air method, pressure influences density, which helps reflect real atmospheric states when humidity is included.
Humidity introduces water vapor, which lowers the mixture’s average molecular mass. That can slightly increase sound speed. The effect is modest, but it matters for calibration work and precise outdoor measurements.
Gamma is the ratio of specific heats used in sound-speed relations. For air it is near 1.40. You might vary it for sensitivity studies or when modeling gases that deviate from standard air behavior.
The built-in pressure estimate uses a standard troposphere relationship that is most reliable up to about 11,000 m. Above that, temperature profiles and formulas change, so a different atmospheric model is required.
No. The examples are rounded and meant for sanity checks and demonstrations. Your computed value depends on the selected model and the exact inputs, especially temperature, pressure, relative humidity, and gamma.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.