Amplifier watts are not wall watts
A sound system labeled "6,000 W" doesn't draw 6,000 W from the wall all night. Music has a high crest factor: average power is usually one-eighth to one-third of the amplifier's rated continuous output, depending on how compressed and loud the music is. On top of that, amplifiers lose some energy as heat – modern Class D amplifiers are 70 – 90 % efficient, older Class AB designs about 50 %.
Wall power ≈ rated power × average fraction ÷ efficiency + idle + other gear · Amps = watts ÷ volts
Typical circuit capacity
| Circuit | Rated | 80 % continuous | At 120 V | At 230 V |
|---|
| 15 A | 15 A | 12 A | 1,440 W | – |
| 16 A | 16 A | 12.8 A | – | 2,940 W |
| 20 A | 20 A | 16 A | 1,920 W | – |
| 32 A | 32 A | 25.6 A | – | 5,890 W |
Planning power for an event
- Find out which outlets share a breaker – several outlets in a room are often on one circuit.
- Spread the load: subwoofer amplifiers draw the most; give them their own circuits.
- Separate audio and lighting to avoid dimmer buzz and trips.
- Use proper distribution: heavy-gauge extension cables, power distros with breakers and ground continuity.
- Check voltage under load: low voltage makes amplifiers shut down or distort.
Generators for outdoor shows
Choose a generator rated at least 25 % above your average draw, with clean, stable output – inverter generators are preferred for audio. Place it far from the stage and audience, run cables safely, and use ground-fault protection where required. For large events, a professional power provider and electrician are the safe choice.
Electrical work must follow local codes. These are planning estimates, not electrical design.
Frequently asked questions
How many amps does a PA system draw?
A 2,000 W Class D PA at loud levels typically averages around 600 – 800 W, or about 5 – 7 A at 120 V.
How many speakers can I run on a 15 amp circuit?
At 120 V you have about 1,440 W continuous. That's typically two to four powered PA speakers at loud levels.
What size generator for a DJ setup?
Many DJ rigs with powered speakers and subs need 2,000 – 5,000 W of generator capacity; add 25 % margin.
Why does my amp trip the breaker?
Bass peaks draw high current briefly. Spread amplifiers over several circuits and avoid sharing with lights or heaters.
What is crest factor in audio?
The ratio between peak and average levels. Music typically averages 1/8 – 1/3 of peak power.
About PowerDistro
PowerDistro is an independent, free calculator for planning power for PA systems, bands and events. Results are estimates based on typical amplifier efficiency and music crest factor; follow local electrical codes and use a qualified electrician for permanent or high-power installations. We are not affiliated with any equipment manufacturer.
Every formula on this page runs entirely in your web browser. The numbers you type are never uploaded, stored or shared. Our goal is simple: give you an honest starting point so you can compare product specifications with confidence and avoid paying for capacity you do not need – or buying something too small to do the job.
The methodology combines widely published engineering rules of thumb, manufacturer data sheets and the electrical code practices that installers use every day. We review the assumptions regularly and update the calculator when typical product specifications change.
Privacy Policy
Last updated: October 28, 2026
This Privacy Policy explains how PowerDistro ("we", "us") handles information when you visit this website. By using the site you agree to this policy.
Information we collect
We do not require registration and we do not ask for your name, address or payment details. Values entered into the calculator are processed locally in your browser and are not transmitted to our servers. Like most websites, our hosting provider may automatically record standard server log data such as IP address, browser type, referring page and time of visit for security and performance purposes.
Cookies and advertising
We use Google AdSense to show advertisements that keep this tool free. Third-party vendors, including Google, use cookies to serve ads based on a user's prior visits to this website or other websites. Google's use of advertising cookies enables it and its partners to serve ads to users based on their visit to this site and/or other sites on the Internet. You may opt out of personalized advertising by visiting Google Ads Settings, or opt out of some third-party vendors' use of cookies for personalized advertising at www.aboutads.info (US) or www.youronlinechoices.eu (Europe). To learn more, see How Google uses information from sites or apps that use its services.
Visitors from the European Economic Area, the United Kingdom and Switzerland are shown a consent message powered by a Google-certified consent management platform, where you can accept, reject or manage cookie choices. You can change your choices at any time from the privacy link displayed by that message. Some visitors may also be offered the option to view a short ad or complete another offer in exchange for access to the content; this choice is provided by Google and is entirely optional where alternatives are offered.
Analytics
We may use privacy-friendly, aggregated statistics to understand which features are used. These statistics do not identify you personally.
Your rights
Depending on where you live (for example under the GDPR or the CCPA/CPRA), you may have the right to access, correct or delete personal data and to object to certain processing. Because we do not keep personal data from the calculator, most requests can be handled by clearing cookies in your browser. For any other request, contact us at the address above.
Children
This site is intended for a general adult audience and is not directed at children under 13. We do not knowingly collect personal information from children.
Changes to this policy
We may update this policy from time to time. The date at the top of this section shows when it was last revised.
Terms of Use & Disclaimer
The calculator and articles on this website are provided free of charge for general information and educational purposes only. Results are estimates based on typical values and simplifying assumptions; real-world performance depends on the specific product, installation, climate, wiring and how you use your equipment.
Nothing on this site is professional engineering, electrical or financial advice. Always follow the manufacturer's instructions and local electrical codes, and have permanent installations, transfer switches and grid-connected systems designed and installed by a licensed electrician or qualified installer. Never operate fuel-burning generators indoors or in enclosed spaces – carbon monoxide can kill within minutes.
The site is provided "as is" without warranties of any kind. To the fullest extent permitted by law, PowerDistro is not liable for any loss or damage arising from the use of, or reliance on, the information or results provided. Product and brand names mentioned belong to their respective owners and are used for identification only. You may use the calculator for personal and commercial purposes, but you may not copy or republish the site content without permission.
PowerDistro