What this tool answers
You need a first-pass portable inverter size before buying. Enter continuous (running) watts for devices you will run together and the highest starting (surge) watts among those loads. The calculator names the smallest class on this site’s ladder — 1800/2900, 3200/4200, or 6800/10000 — that clears both numbers, or returns NO_MATCH. It is not an electrical design, transfer-switch plan, or substitute for manufacturer instructions.
Running watts vs surge watts
Running watts are continuous draw. Surge watts are brief peaks when inductive motors start. A fridge that runs at a few hundred watts may need well over a thousand at compressor start. Size for both: continuous total must stay under the generator’s running rating, and the worst start must stay under peak.
Class ladder on this site
Classes use published VEVOR US inverter ratings checked 2026-09-10: (1) 1800 running / 2900 peak, (2) 3200 / 4200, (3) 6800 / 10000. No verified ~5500/7000 inverter SKU was documented on that date, so the third step uses the larger 6.8 kW / 10 kW peak unit. Matching rule: smallest class where running ≥ your continuous AND peak ≥ your surge.
When the answer is NO_MATCH
If your continuous watts exceed 6800 or your surge exceeds 10000 (or both), this site returns NO_MATCH for its published ladder. Typical next steps: reduce simultaneous loads, stagger motor starts, or look at a higher-rated generator outside this screen. Do not force an undersized inverter.
Outdoor use, CO, and backfeed
Operate outdoors only with open air — never in a home, garage, tent, or enclosed space. Carbon monoxide is odorless and deadly; a CO sensor on the generator does not make indoor use safe. Never backfeed house wiring through a receptacle or improvised jumper. Connecting a generator to building circuits requires a licensed electrician and a properly installed transfer switch. Improper backfeed can electrocute utility workers and damage equipment.
Sources
VEVOR US inverter generator product pages for running/peak watt claims dated in products.json (checked 2026-09-10). Consumer generator sizing practice separating continuous and starting watts. Safety framing follows common manufacturer warnings: outdoor operation, CO hazard, and prohibition on connecting to household wiring without approved transfer equipment.