Home Power Facts Portable generator
Generac iQ3500
The Generac iQ3500 is an inverter generator rated 3,000 W running and 3,500 W starting on gasoline. It can run 28 of the 29 household loads we track. The manufacturer rates it at 14.1 hours on a 2.6 gal tank at 25% load, about 4.4 gallons a day at that load.
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Specs
| Type | Inverter (clean power for electronics) |
|---|---|
| Fuel | gasoline[source]Full model name on the official page: iQ3500 (3500i) with COsense, 50ST, model 7723. SUBSTITUTION: the requested GP3500iO (open-frame, model 7128) no longer has a product page on generac.com (old URLs go to /not-found/ and it is not in the current portable generator list). Its 2018 spec sheet is still hosted at https://www.generac.com/globalassets/products/residential/portable-generators/spec-sheets/7128-gp3500io-portable-generator-spec-sheet.pdf (3000 W running / 3500 W starting, 2.37 gal, 11 h at 25% / 8 h at 50%, 74.3 lb). The current Generac equivalent is the enclosed iQ3500 / 3500i with COsense (7723), which is not open-frame. The page title says 'Gas Powered'. |
| Running watts (gasoline) | 3,000 W[source]AC Rated Output Running Watts 3000 (spec sheet Rev. C 05/17/2024). The product page spec block also shows 3,000. |
| Starting watts (gasoline) | 3,500 W[source]AC Maximum Output Starting Watts 3500. The product page spec block shows 'Starting Watts: 0', which is a page data error. |
| Fuel tank | 2.6 gal[source]Fuel Tank Capacity 2.6 gal (10 L). The product page shows the same figure. |
| Runtime on a full tank | 14.1 h[source]Run Time at 25% of Rated Load 14.1 h. At 50% load it is 8.9 h, matching the product page's '8.9 hrs of run time at 50% load'. at 25% load |
| Noise | Not publishedNeither the spec sheet nor the product page gives a dB figure. They only say 'Ultra-Quiet'. |
| 240 V outlet | No[source]120 VAC only. Outlets: (1) 120V 20A 5-20R duplex, (1) 120V 30A L5-30R twist-lock, 5V USB ports and parallel outlets. |
| CO shut-off sensor | Yes[source]COsense Technology, described as 'Stops, Alerts, Saves'. Generac's GP-series owner's manual says COsense shuts off the engine when CO accumulates. |
| Weight | 109.1 lb[source]Unit Weight 109.1 lb (49.5 kg). Shipping weight is 120.2 lb. |
| List price | Not publishedgenerac.com shows no price. It uses a PriceSpider where-to-buy widget, and shop.generac.com is a B2B portal. Retailer prices not used. Checked 2026-10-19. |
Fuel cost: about $1.06 per kWh at the stated load (0.25 gal/kWh × $4.33/gal, the EIA US average). This applies at the stated load only.
What it can run
"Yes" means the running watts fit within 3,000 W and the startup surge within 3,500 W, and the load runs on 120 V. Unlike a battery, a generator runs as long as it has fuel, so there is no runtime per appliance; see fuel use above.