# Sound Pressure Level Converter (Pa / dB SPL re 20 µPa)

Convert sound pressure between linear units (Pa, µPa, µbar, mbar) and the decibel sound pressure level dB SPL (Lp = 20·log₁₀(p / 20 µPa), reference p₀ = 20 µPa = 2e-5 Pa RMS, per ISO 1683). Supports bidirectional linear↔logarithmic conversion. Calibration anchor: 1 Pa → 20·log₁₀(1/2e-5) ≈ 94 dB SPL. Reference values: threshold of hearing 20 µPa (0 dB), speech ≈ 0.02 Pa (60 dB), rock concert ≈ 20 Pa (120 dB), pain threshold ≈ 200 Pa (140 dB).

> Canonical page: https://elysiatools.com/en/tools/sound-pressure-level-converter

- **Category:** Math & Numbers

- **Keywords:** sound pressure, sound pressure level, SPL, Lp, decibel, dB SPL, pascal, Pa, µbar, microbar, acoustics, 20 log, microphone calibration

## Overview

Convert sound pressure between Pa, µPa, µbar, mbar, and dB SPL referenced to 20 µPa. Enter a value, choose the input and output units, and set the desired decimal places for a clear JSON result.

## Inputs

- **Input unit** (select)
- **Value** (number): Sound pressure in the selected Input unit. Must be non-negative (linear) or finite (dB).
- **Output unit** (select)
- **Decimal Places** (number)

## When to use

- Convert microphone or acoustic measurements from pascals to dB SPL.
- Convert a dB SPL reading into linear sound pressure units such as Pa or µPa.
- Compare acoustic reference values using consistent pressure units.

## How it works

- Enter a non-negative linear pressure value or a finite dB SPL value.
- Select the input unit: Pa, µPa, µbar, mbar, or dB SPL.
- Select the output unit and choose between 0 and 10 decimal places.
- The converter applies the dB SPL reference of 20 µPa and returns the converted value with related unit values in JSON.

## Use cases

- Microphone calibration using the 1 Pa to approximately 94 dB SPL reference.
- Acoustic measurement work requiring conversions between dB SPL and pascals.
- Checking familiar sound-pressure references such as speech or hearing-threshold levels.

## Frequently asked questions

### What reference does this converter use for dB SPL?

It uses 20 µPa, equal to 2e-5 Pa RMS, as the dB SPL reference pressure.

### What is 1 Pa in dB SPL?

1 Pa is approximately 93.98 dB SPL, commonly rounded to 94 dB SPL.

### Can I convert dB SPL back to pascals?

Yes. Select dB SPL as the input unit and Pa as the output unit.

### Which pressure units are supported?

The converter supports Pa, µPa, µbar, mbar, and dB SPL.

### What values can I enter?

Linear pressure values must be non-negative. dB SPL inputs must be finite numbers.

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