A wattage figure on a small speaker describes the amplifier's rated output into the driver. It correlates loosely with maximum volume and not at all with sound quality, which depends on the driver, the enclosure volume and the tuning.

This is why a well-designed 5 watt speaker can sound better than a poorly designed 15 watt one, and why the larger number is worth paying for only when the enclosure and drivers justify it. A 15 watt unit with a three inch and one inch driver pair is a different class of product from a 3.2 watt metal capsule, and the difference is the driver arrangement as much as the power.

Battery capacity interacts with this directly. A higher output speaker drains its cell faster at the same volume, so playtime claims have to be read against the output figure rather than in isolation.

For a listing, state the wattage and the driver configuration together. A customer comparing two speakers on watts alone will be disappointed by one of them, and the disappointment arrives as a return.