Micropascal to Decibel SPL (re 20 µPa) Converter

20 µPa is 0 dB SPL. Convert micropascals (µPa) to decibels SPL (dB SPL) below: type a value and the result updates as you type.

µPa to dB SPL calculator

Result

Micropascal to Decibel SPL (re 20 µPa) conversion

1 µPa ≈ -26.02059991 dB SPLone micropascal in decibels SPL

1 dB SPL ≈ 22.44036909 µPaone decibel SPL in micropascals

Micropascal (µPa): One millionth of a pascal. The reference sound pressure in water is 1 µPa.

Decibel SPL (re 20 µPa) (dB SPL): Sound pressure level in air: 20 times the base-10 logarithm of the RMS sound pressure divided by the reference pressure of 20 µPa. 0 dB SPL is 20 µPa, about the quietest sound a young adult can hear.

Source:Micropascal: SI Brochure, 9th edition (BIPM, 2019); Decibel SPL (re 20 µPa): ISO 1683:2015, Acoustics: Preferred reference values for acoustical and vibratory levels

How to convert micropascals to decibels SPL

To convert micropascals to decibels SPL, divide the amount by 20, take the base-10 logarithm, then multiply by 20.

Formula

dB SPL = 20 × log₁₀(µPa ÷ 20)

Examples

20 µPa = 20 × log₁₀(20 ÷ 20) = 0 dB SPL
2000 µPa = 20 × log₁₀(2000 ÷ 20) = 40 dB SPL
1000000 µPa = 20 × log₁₀(1000000 ÷ 20) ≈ 93.97940009 dB SPL

Micropascal to Decibel SPL (re 20 µPa) conversion table

Micropascal to Decibel SPL (re 20 µPa)
Micropascal (µPa)	Decibel SPL (re 20 µPa) (dB SPL)
1 µPa	-26.02059991 dB SPL
20 µPa	0 dB SPL
200 µPa	20 dB SPL
2000 µPa	40 dB SPL
20000 µPa	60 dB SPL
200000 µPa	80 dB SPL
1000000 µPa	93.97940009 dB SPL

Values rounded to 10 significant digits where needed.

Frequently asked questions

What is 20 µPa in dB SPL?: 20 µPa is 0 dB SPL. To convert micropascals to decibels SPL, divide the amount by 20, take the base-10 logarithm, then multiply by 20.
How do I convert decibels SPL to micropascals?: To convert decibels SPL to micropascals, divide the level by 20, raise 10 to that power, then multiply by 20. The formula is µPa = 20 × 10^(dB SPL ÷ 20).
Is this conversion exact?: Yes. Both units have exact definitions and the factor 20 is exact. Displayed results are only rounded when they have many decimal places.