dB SPL to Pascals Calculator
Sound pressure level in decibels and sound pressure in pascals are two ways of describing the same thing. The decibel scale is logarithmic and referenced to 20 micropascals, the threshold of human hearing; pascals are the linear physical pressure. This calculator converts both ways: enter a level in dB SPL to get the pressure in pascals, or enter a pressure in pascals to get the level. It is useful for microphone calibration, acoustic measurement, and understanding how the decibel numbers on a sound level meter relate to real pressure. The reference pressure is editable for non-standard references.
dB SPL to pascals formula
p0 = reference pressure = 20 micropascals = 0.00002 Pa
Pressure (Pa) = p0 * 10^(level / 20)
Level (dB) = 20 * log10(pressure / p0)
The factor of 20 comes from sound power being proportional to pressure squared: a 20 decibel rise multiplies pressure by ten, and a 6 decibel rise roughly doubles it.
Worked example
94 dB SPL with the standard 20 micropascal reference: pressure = 0.00002 * 10^(94 / 20) = 0.00002 * 50,118.72 = 1.00 Pa, which is why 94 dB SPL is a common 1-pascal calibration level. Reversing, 1 pascal gives 20 * log10(1 / 0.00002) = 93.98 dB SPL.
dB SPL to pascals: frequently asked questions
What is the reference for dB SPL?
Sound pressure level in decibels is referenced to 20 micropascals (20 millionths of a pascal), the standard reference pressure p0 for airborne sound defined in ISO 1683. It corresponds roughly to the quietest sound a healthy young ear can detect at 1,000 hertz, which is why 0 dB SPL is the threshold of hearing.
What is the dB SPL to pascals formula?
Pressure in pascals = p0 times 10 to the power (level in decibels divided by 20), where p0 is 0.00002 pascals. The factor is 20 rather than 10 because sound pressure level is a ratio of pressures, and power is proportional to pressure squared. To go back: level = 20 times log10(pressure divided by p0).
What pressures correspond to common levels?
0 dB SPL is 20 micropascals (0.00002 Pa). 94 dB SPL, a common calibration level, is almost exactly 1 pascal. 120 dB SPL, near the threshold of pain, is about 20 pascals. Each 20 decibel step multiplies the pressure by ten.
Is sound pressure the same as sound power?
No. Sound pressure is what a microphone or ear senses at a point, measured in pascals. Sound power is the total acoustic energy a source emits, measured in watts. They are related but distinct; this calculator converts sound pressure level, not sound power level.
Official sources
- International Organization for Standardization: ISO 1683 reference values for acoustic levels.
- U.S. National Institute of Standards and Technology: nist.gov.
Reviewed by the CalculatorHub team, edited by James Graham, 19 June 2026. See our methodology.