Frequency (Hz) C-weighting (dB)
6.3 -21.3
8 -17.6
10 -14.3
12.5 -11.3
16 -8.4
20 -6.2
25 -4.4
31.5 -3.0
40 -2.0
50 -1.3
63 -0.8
80 -0.5
100 -0.3
125 -0.2
160 -0.1
200 0.0
250 0.0
315 0.0
400 0.0
500 0.0
630 0.0
800 0.0
1000 0.0
1250 0.0
1600 -0.1
2000 -0.2
2500 -0.3
3150 -0.5
4000 -0.8
5000 -1.3
6300 -2.0
8000 -3.0
10000 -4.4
12500 -6.2
16000 -8.6
20000 -11.3

Using the Table

To determine C-weighted decibel values (dBC), add the C-weighting factor for the corresponding one-third octave frequency band to the unweighted decibel level (dB).

Equation

dBC = dB + C–weighting\ factor

dBC Calculator

Learn More

What is a Decibel?

Learn how decibels work.

Calculating Decibel Levels

Learn the math behind decibel levels

Adding Decibels

Getting wrong answers? Learn to fix them here.

This table was created with expressions from IEC 61672-1:2013 Electroacoustics – Sound level meters – Part 1: Specifications to calculate C-weighted levels. These expressions, along with additional information, can be found here.