ConverterHub

Decibel to Linear Calculator

Enter a decibel value and choose power or field to get the linear ratio.

How it is calculated

For a power-type quantity (power, energy, intensity) the linear ratio is ratio = 10dB/10. For a field-type quantity (voltage, current, sound pressure) it is ratio = 10dB/20. Choose the basis with the mode field; power is used if none is given. The dB value can be negative, which gives a ratio below 1 (a loss).

The ratio is shown with four decimals. Very large ratios (one million or more) and very small ones (below 0.0001) switch to scientific notation such as 1.0000e+7. The result is a plain multiplier with no unit. The tool treats dB as a ratio between two values, so absolute levels like dBm or dBV need their reference converted separately.

Worked example

Convert +3 dB on the power basis: ratio = 103/10 = 100.3 = 1.9953. So +3 dB roughly doubles the power. On the field basis, the same 3 dB would be 103/20 = 1.4125, a voltage gain of about 1.41. For 20 dB the power basis gives 100.0000 while the field basis gives 10.0000.

Try this example →

Common mistakes

  • Choosing the power basis for a voltage or sound-pressure figure: dB for field quantities uses 20, not 10, so the ratio would be the square of what it should be.
  • Adding or averaging linear ratios as if they were dB: dB values add when ratios multiply, so +3 dB followed by +3 dB is +6 dB, a power ratio of about 3.98, which is 1.9953 × 1.9953, not 1.9953 + 1.9953.
  • Rounding 3 dB to exactly 2: the true power ratio is 1.9953, and the error grows when you chain several stages.
  • Treating a dBm or dBW level as a pure ratio: those are relative to 1 mW or 1 W, so the ratio you get is relative to that reference, not a power in watts.

About this calculator

Decibels express a ratio on a logarithmic scale, which compresses huge real-world ranges — like the difference between a whisper and a jet engine — into manageable numbers, but that also means dB values can't simply be added or divided the way linear quantities can. Converting back requires knowing whether the dB value represents a power ratio (10^(dB/10), used for quantities like power, energy, or intensity) or a field/amplitude ratio (10^(dB/20), used for quantities like voltage, current, or sound pressure) — the factor-of-two difference in the exponent trips up beginners constantly.

This calculator takes a decibel value and your choice of power or field basis and returns the equivalent linear ratio. Audio engineers setting gain staging, RF and telecom engineers computing link budgets, and electronics students converting amplifier or antenna specs use it to move between the dB figures on a datasheet and the actual multiplicative ratio they represent.

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