When looking to buy a speaker, knowing its wattage is not enough to determine how loud it will play. There is a crucial factor to consider, which is called sensitivity or efficiency. Sensitivity tells you how efficiently the power you’re putting into the speaker is being turned into a critical power like mechanical force of pushing the air.

For instance, a 200-watt speaker with low sensitivity will use a lot of watts but not produce enough sound pressure. On the other hand, a 100-watt speaker with high sensitivity will play just as loud as the 200-watt speaker.

To determine how loud a speaker is, you need to consider both the sensitivity and the sound pressure level (SPL). SPL is measured in decibels (dB) and is the actual acoustical force that you’re getting out of the speaker.

Let’s take a typical floor-standing speaker, which has a sensitivity of 90 dB for 1 watt of power at 1-meter distance. If you want to compare speakers, you need to use the same power and distance measurements.

To calculate the SPL, you need to double the power to raise it by three decibels. For example, a 100-watt speaker with 90 dB sensitivity will play at 93 dB with 2 watts of power, 96 dB with 4 watts, and 102 dB with 16 watts.

Remember that wattage and sensitivity are not directly aligned with how loud a speaker can play. You need to consider both factors to determine the speaker’s maximum sound pressure level.

In conclusion, when shopping for a speaker, pay attention to both its wattage and sensitivity to determine how loud it will play.