Knowing the typical wattage for mobile and house DJ gear is essential to buying the right gear the first time, saving tons of money in the long run. Wattage ratings on DJ gear can be divided into primary speakers, subs and power amps. As a club owner or event promoter, you will need each at the right wattage to run your nights. As a mobile DJ, you will need DJ gear that's at the right wattage and still portable for you.
Wattage, technically, is a measure of the rate of energy conversion, or how much energy your DJ gear will be pulling from the wall. Wattage as applied to speakers, subs, heads and the like is a general indicator of how much volume you will be able to achieve. Keep in mind that more wattage does not mean better. It makes little difference if you are running DJ gear at high wattage if the gear can't handle the volume. You can't have any unwanted distortion of the bass.
Gear wattage is measured as a rate into a certain number of ohms, an ohm being a rating of the amount of electrical resistance. All speakers and subs must be able to handle the energy resistance the power amp spits out.
House DJ gear, supplied by the club owner or event promoter, can afford to be at higher typical wattage because budgets are usually larger, and because it does not have to be loaded into a truck every time the DJ goes to work. Typical wattage for house DJ gear is 1400 to 2000 watts stereo into four ohms powering the speakers, and 2000 to 5000 watts into four-ohm mono bridge mode for the sub. You'll need separate amps for your primary channel and sub.
Due to budget and limited truck space, mobile DJs who must provide their own DJ gear typically can get away with using lower wattage. Mobile gear usually is 400 to 500 watts into 4 ohms in stereo mode for the two primary speakers, and 800 watts or so in mono mode for the sub. If you are DJing a small club you can probably get away with running a single power amp without a sub or powered 15-inch monitors, but don't expect that tub-thumping bass.
Keeping all these watts and ohms in mind, how much can a club owner, or a mobile DJ, expect to spend on their sound gear? Figure on $1,000 to $1,800 for a decent mobile DJ rig, and $4,000 to $5,000 on a DJ rig good enough for a medium-size club. You can, of course, get by spending more or less. It just depends on how important your sound is. Especially for the professional working mobile DJ, showing up for a gig with gear that just doesn't have the wattage behind it will likely lead to not being asked back.
It is extremely important to understand impedance, rated in ohms, when matching your power amps with your speakers and subs as a DJ. You'll need to understand things like bridges and crossovers well beyond the scope of this article. Try the International System of Units website listed below to better understand all these watts and ohms and what they mean, or buy a pre-matched DJ sound package that will contain all the correct gear at proper matching wattages. Ultimately, the more you know as a DJ or soundman cannot hurt your marketability and success.