Speaker wattage is defined as RMS which is how much the amplifier will put out per channel. If you want to know what wattage speakers do I need? Here is the answer 25 watts means 25 watts a channel and this is the pure wattage. Four-ohm speaker needs less power than the 8-ohm speaker and most speakers are 8 ohms. Always try to found efficient speakers like 4-ohm where the amplifier does not use that much wattage to play.
A watt is a unit of energy named after James watt who developed the practical steam engine. In the audio world, watts are used to measure the power handling capabilities of speakers and the power-output capabilities of amplifiers.
Wattage relates speakers:
Nonpowered (passive) speakers do not have power amps and the wattage ratings of a nonpowered speaker, referring to its power-handling capability. There are two general values for power rating.
Root mean square (RMS)
RMS rating is the amount of power that can be applied to the speaker under normal circumstances and its value refers to how much continuous power the speaker can handle. A speaker with high power ratings uses a large voice coil that allowing more heat to be dissipated. Use this power rating to match the speaker RMS capacity to an amplifiers RMS output.
Peak power rating
It maximum amount of power that can be applied for a short period without causing damage and its rating is exceeded for an extended period. Mostly do not use this power rating for matching speakers to amplifiers.
Here the question is how many watts do I need for speakers? And the answer depends on your speaker. For example, if your speaker rated at 50 watts RMS and 150 watts peak then it can handle 50 watts of continuous power. Another example if your speaker is rated at 200 watts that it can handle 200 watts of power.
Speaker’s ability to handle power is the factor that will determine how loud it can be efficiency, sensitivity and dispersion characteristic will contribute to its apparent loudness. Speakers producing a narrow range of frequencies may be able to get much louder than when trying to reproduce a full range of frequencies and it is not safe. Form this you have known how much watts are good for speakersand use correct watts for your speaker for good maintains.