dB(A) → dB(C) aprox
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
About this calculator
The dB(A) → dB(C) approx calculator converts sound levels weighted in A (dB(A)) to approximate C-weighted (dB(C)) by adding 3 dB. This estimation is based on the typical difference between A and C weightings, which consider different frequency ranges. It's useful for noise analysis where estimating C-scale measurements from A-scale data is needed.
The calculation follows the formula: dB(C) ≈ dB(A) + 3 dB. A-weighting attenuates low frequencies, while C-weighting is more linear and includes more low frequencies. This simplified conversion is valid for contexts like industrial noise assessment or equipment with low-frequency components.
Use this tool in acoustic design, occupational safety, or environmental studies. However, for precise measurements, consult calibrated devices that directly measure in dB(C). This approximation cannot replace detailed analyses by specialized laboratories.
Frequently asked questions
Why add 3 dB to convert dB(A) to dB(C)?
The 3 dB difference represents the typical low-frequency attenuation between A and C weightings. C-weighting includes more low frequencies, adjusting the value by +3 dB.
When should I use this approximate conversion?
Use it for quick industrial noise analyses, equipment with low frequencies, or when calibrated C-weighted meters are unavailable.
Is this tool accurate for legal compliance?
No, it's an approximation. For legal compliance, use certified equipment that directly measures dB(C).
Can I trust this calculator for acoustic projects?
It provides an initial estimate. Detailed projects require measurements with a spectrum analyzer or experts.