Calculadora de Intensidade Sonora (dB)
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
L = 10·log₁₀(I/I₀)
About this calculator
This calculator converts sound intensity (I, in W/m²) to sound intensity level (L, in dB) using the formula L = 10·log₁₀(I/I₀), where I₀ = 1×10⁻¹² W/m² is the threshold of hearing. The result is expressed in decibels, a logarithmic unit that reflects human perception of sound. The tool is useful for students, audio professionals, and acoustic engineers.
To use, enter the sound intensity value in watts per square meter. The calculator applies base-10 logarithm and multiplies by 10. For example, an intensity of 1×10⁻⁶ W/m² yields 60 dB, equivalent to normal conversation. Values above 120 dB can cause pain and hearing damage.
This tool is ideal for comparing sound levels from different sources, calculating noise exposure, or sizing hearing protection. Remember that the decibel scale is logarithmic: a 10 dB increase corresponds to a tenfold increase in physical intensity, but is perceived as a doubling of loudness.
Cautions: the formula assumes standard reference I₀ = 1×10⁻¹² W/m². In environments with background noise, measurement may be inaccurate. Always use calibrated instruments for real measurements. This calculator is educational and does not replace professional equipment.
Frequently asked questions
What does 0 dB mean?
0 dB corresponds to the threshold of human hearing, the minimum sound intensity a healthy ear can detect, which is I₀ = 1×10⁻¹² W/m².
Why is the decibel a logarithmic scale?
Because human perception of sound is not linear; we use a logarithmic scale to compress a wide range of intensities (from 10⁻¹² to 10⁰ W/m²) into practical values from 0 to 120 dB.
What is the difference between sound intensity and sound intensity level?
Sound intensity is the power per unit area (W/m²), a physical measure. Sound intensity level (dB) is a logarithmic scale comparing that intensity to a reference value.
Can I use this calculator to measure noise in my workplace?
The calculator provides an estimate, but for accurate occupational noise measurements, use a calibrated sound level meter and follow regulatory standards.
What happens if I enter an intensity value lower than 10⁻¹² W/m²?
The result will be negative because the logarithm of a number less than 1 is negative. This indicates a level below the threshold of hearing.