Convert dB to a normal (linear) value: enter decibels and choose power or amplitude to get the ratio, or convert a linear ratio back to dB.

Power uses 10 log; amplitude (voltage, current, pressure) uses 20 log and assumes 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 Pref = 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 Pref = 1 W. Formula: P = Pref × 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 (linear) 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.