Sound Converter
Convert sound pressure levels between dB SPL, Pa, and µPa, or sound intensity between dB IL and W/m². Enter a Sound value and choose the From unit and To unit.
Convert Sound Level, Pressure, Intensity, and Power
Sound Converter Formula
Where:
- \(p\) — sound pressure in pascals (Pa)
- \(p_0\) — reference sound pressure in air, \(20\times10^{-6}\) Pa
- \(L_p\) — sound pressure level in dB SPL
This formula converts a sound pressure level to its corresponding pressure. The calculator also supports the reverse conversion, conversions involving micropascals, and separate sound intensity conversions.
Sound Converter – Calculation Example
Example: convert the default Sound value of 85 dB SPL to Pa.
\[p=(20\times10^{-6})10^{85/20}\approx0.355655882\ \mathrm{Pa}\]
Result: 0.355656 Pa, rounded to six decimal places.
How to use the calculator
- Enter a nonnegative number in Sound value. The default is 85.
- Choose the value’s current unit in From unit.
- Choose the desired unit in To unit. The default selections convert dB SPL to Pa.
- Read Converted Sound Value. If it says “Unsupported conversion,” select one of the supported unit pairs below.
The calculator supports conversions in either direction between dB SPL and Pa, dB SPL and µPa, and dB IL and W/m². It does not directly convert Pa to µPa, even though those are both pressure units; for that conversion, use a pressure converter or multiply Pa by one million.
What sound pressure and intensity levels mean
Sound pressure is the pressure variation associated with a sound wave. Pascals (Pa) and micropascals (µPa) express its magnitude on a linear scale: \(1\ \mathrm{Pa}=1{,}000{,}000\ \mathrm{\mu Pa}\). Sound pressure level, or dB SPL, expresses pressure as a logarithmic ratio to the calculator’s reference of \(20\ \mathrm{\mu Pa}\) in air. Thus, 0 dB SPL corresponds to 20 µPa, not to zero pressure.
For pressure, \(L_p=20\log_{10}(p/p_0)\). An increase of 20 dB SPL corresponds to ten times the pressure; an increase of approximately 6 dB corresponds to twice the pressure. These relationships describe pressure ratios, not necessarily how much louder a sound will seem to a listener. Perceived loudness also depends on frequency and other conditions. If you need to convert between cycles per second and other frequency units, use the frequency converter.
Sound intensity describes acoustic power passing through an area and is measured in watts per square meter (W/m²). The calculator uses a reference intensity of \(I_0=10^{-12}\ \mathrm{W/m^2}\) and the relationship \(L_I=10\log_{10}(I/I_0)\). A 10 dB IL increase means ten times the intensity. Consequently, 0 dB IL corresponds to \(10^{-12}\ \mathrm{W/m^2}\), not zero intensity.
Although both levels use decibels, dB SPL and dB IL describe different physical quantities. Turning a measured pressure into intensity requires information about the acoustic medium and wave conditions; selecting one decibel unit in place of the other would not provide that information. This calculator keeps its pressure and intensity conversions separate.
Assumptions and practical limits
- Reference values are fixed. The calculator uses 20 µPa for dB SPL and \(10^{-12}\ \mathrm{W/m^2}\) for dB IL. Check the reference used by your source before comparing results.
- Use positive linear values for logarithmic conversions. Zero Pa, zero µPa, and zero W/m² have no finite decibel level because their logarithms are undefined. Negative linear inputs are not accepted.
- Negative decibel inputs are not available. The Sound value field has a minimum of zero, even though levels below 0 dB SPL or 0 dB IL are mathematically possible relative to their references.
- Results are rounded to six decimal places. Very small intensities can therefore display as 0 W/m². For example, 0 dB IL represents \(10^{-12}\ \mathrm{W/m^2}\), but the displayed result rounds to 0 W/m²; the underlying intensity is not zero.
- This is a unit conversion, not a noise-exposure assessment. It does not apply frequency weighting, account for exposure duration, or calculate a time-averaged level. It also does not convert sound power in watts (W).
For meaningful measurements, confirm whether a reported pressure is an RMS value or a peak value and whether a reported decibel level is weighted, such as dB(A). A change in those measurement conventions can change the interpretation even when the unit label looks similar.
Frequently Asked Questions
How do I calculate dB SPL from a pressure measurement by hand?
Divide the measured RMS pressure by 20 µPa, take the base-10 logarithm, and multiply by 20. For example, 0.2 Pa is 10,000 times the reference pressure, so its level is \(20\log_{10}(10{,}000)=80\) dB SPL. Use an RMS pressure measurement; substituting a peak pressure gives a different level.
What is a typical sound level for a quiet room or a conversation?
A quiet room might measure around 30–40 dB SPL, while ordinary conversation at a short distance is often around 60 dB SPL. These are rough examples, not target values: background noise, distance, room acoustics, and the measurement method can all change the reading. A single number also does not describe which frequencies are present.
Does adding 3 dB mean the sound pressure doubles?
No. A 3 dB rise corresponds to approximately twice the intensity but only about 1.41 times the RMS pressure under comparable conditions. Two equally loud, independent sound sources often produce a combined level about 3 dB higher than either source alone. That rule may not hold for coherent sources or when one source is much louder than the other.
How much do peak and RMS sound pressure levels differ?
For a pure sine wave, peak pressure is \(\sqrt{2}\) times RMS pressure, making its peak-based level about 3.01 dB higher. There is no universal 3 dB correction for speech, music, or other complex sounds: their peak-to-RMS ratios vary. Check which pressure measure your instrument reports before comparing readings.
Can sound pressure be used to estimate sound intensity?
Yes, but only with assumptions about the sound field and medium. For a traveling plane wave, intensity can be estimated as \(I=p_{\mathrm{RMS}}^2/(\rho c)\), where \(\rho\) is the medium’s density and \(c\) is sound speed. Reflections, standing waves, and near-field measurements can make that estimate unreliable. A pressure reading alone does not establish intensity in every setting.
Is 85 dB SPL safe to listen to?
You cannot determine a safe exposure time from an unweighted dB SPL reading alone. Hearing-risk guidance generally uses time-averaged, A-weighted levels: for example, NIOSH recommends limiting occupational exposure to 85 dB(A) averaged over eight hours, with shorter durations at higher levels. If exposure is frequent or uncomfortable, measure it appropriately and consider hearing protection.
4 thoughts on “Sound Converter”