What Size Generator for an Outdoor Event
Direct answer
Add up your actual equipment draws, then add 20–30% headroom for startup surges. Rental-industry anchors: 3,000–3,600 W covers a DJ setup, string lights, a fridge and vendor outlets — the typical backyard-wedding load. Move to 5,000–7,500 W once electric catering equipment (grill 1,500–2,400 W, coffee maker 600–1,200 W, warmers 600–1,200 W) and a bigger PA join. Amplifiers alone run 500–2,000 W; string lights are trivial (~0.5 W/bulb).
List loads first, buy watts second
Generator regret is almost always a missing list, not a wrong multiplication: the coffee maker, the second speaker pair, the bounce-house blower that appeared on the day. Write every plugged-in device with its wattage (label or manual), sum the running load, add the biggest single startup surge, then 20–30% margin. If catering runs on propane instead of electricity, most weddings fit comfortably in the 3,000-watt class.
Place the generator downwind and away from the tent (noise and exhaust), run cables along taped routes, and never daisy-chain power strips to reach distance — rent proper distribution cable with the generator.
Assumptions
- Rental-platform and equipment-maker sizing guides (tier-3), US and UK sources consistent.
- Running watts vs surge watts: motors and compressors spike on startup — that's what the headroom covers.
What changes this answer
- Electric catering is the step change — heat-producing appliances dominate every other load.
- Sound systems scale with venue size; a 4-speaker PA can triple the AV draw.
- Cold weather adds heaters (1,500 W+ each) — often the forgotten load.
Sources
- Equipment rental platforms (RNTR, GeneratorsR, Plato Hire UK) — generator sizing — tier 3, verified 2026-07-22
- AV/event power trade — equipment draws — tier 3, verified 2026-07-22
Last checked 2026-07-22. Tiers: 1 government/regulator · 2 industry body · 3 official supplier docs · 4 large surveys · 5 professional material.