Convert dB to a linear power or amplitude value, reverse a ratio to decibels, and scale any reference with percent gain, loss, and attenuation outputs.

Power uses 10 log; amplitude uses 20 log. Voltage/current power comparisons assume equal impedance.

Reference value

Blank uses 1. Output uses the same unit as this reference.

dB to Normal Value Formula

The following formula converts a power or energy dB ratio to a normal value. For amplitude, voltage or pressure ratios, replace 10 with 20; voltage/current power comparisons assume equal impedance.

NV = RV × 10(dB / 10)

Variables:

  • NV is the normal value
  • RV is the reference value (default is 1 if not provided)
  • dB is the decibel value

Multiply the reference by 10 raised to dB/10 for power, or dB/20 for amplitude. Blank reference uses 1; an entered reference scales the output in the same unit.

Decibels to Normal Value Conversion Table (Assumes P_ref = 1 W)
Decibels (dB) Normal Value (W)
-400.0001
-300.001
-200.01
-100.1
-60.251
-30.501
-20.631
-10.794
-0.50.891
01
0.51.122
11.259
21.585
31.995
63.981
1010
1319.953
20100
301000
4010000
* Values rounded to 3 decimals where applicable. Assumes reference P_ref = 1 W. Formula: P = P_ref × 10^(dB/10).

What is a dB (Decibel)?

A decibel (dB) is a logarithmic unit used to express the ratio of two values of a physical quantity, often power or intensity. Decibels are commonly used in acoustics to quantify sound levels relative to a reference value. The decibel scale is logarithmic, meaning that a change of 10 dB represents a tenfold change in intensity.

How to Calculate Normal Value from dB?

The following steps outline how to calculate the normal value from a dB value.

  1. First, determine the dB value you want to convert.
  2. Next, determine the reference value (RV). If not provided, use the default value of 1.
  3. Use the formula NV = RV * 10^(dB / 10) to calculate the normal value (NV).
  4. Finally, select dB to normal value, choose the ratio basis, enter the dB value and optional reference, then select Calculate.

Example Problem:

Use the following variables as an example problem to test your knowledge.

dB value = 20 dB

reference value (RV) = 1 (default); with the power basis, normal value = 1 × 10^(20/10) = 100.