When we're talking about electrical units like voltage, current, and power, it's pretty easy to remember which units use the 10log equation and which use 20log: any units related to power use 10log and the rest use 20log. However, with other units, like sound pressure level, it's not quite as obvious. Below is a list of common units and whether they use 10log or 20log when using decibel units. Also note that any units that use 10log are increased 3dB per doubling, whereas any units that use 20log are increased 6dB per doubling.