Generac GP6500 published runtime
Generac's spec sheet for the GP6500 with COsense (models 7680 and 7683) lists 16.5 hours at 25% load and 11.5 hours at 50% load on a full 7.9-gallon tank.
Older GP6500 versions (for example model 7690) have a smaller 6.9-gallon tank and different runtimes, so check your model number.
Verified specifications
- Manufacturer
- Generac
- Model
- GP6500 with COsense
- Model number
- 7680
- Model codes
- 7680-1 / 7680-2 / 7683-1 / 7683-2 / 7683
- Generator type
- Conventional
- Gasoline: running
- 6,500 watts
- Gasoline: starting / max
- 8,125 watts
- Gasoline: tank
- 7.9 gallons
- Gasoline: published runtime
- 16.5 hours at 25% load on 7.9 gallons
- Gasoline: published runtime
- 11.5 hours at 50% load on 7.9 gallons
- Voltage
- 120/240V
- Frequency
- 60 Hz
- Displacement
- 389cc
- Weight
- 172 lb
- Starting system
- Recoil pull start
- CO safety
- COsense
Source: Generac GP6500 COsense spec sheet (7680 / 7683) — View Generac Specifications ↗
Specifications verified: September 28, 2026
How much gas does the Generac GP6500 use?
- At 25% load: 7.9 gal ÷ 16.5 h ≈ 0.48 gallons per hour
- At 50% load: 7.9 gal ÷ 11.5 h ≈ 0.69 gallons per hour
These are our calculations from Generac's published tank size and runtimes, not Generac figures.
Manufacturer figures vs. our estimates
Only the runtimes listed above are Generac's own published figures. When your load and fuel amount exactly match one of them, the calculator labels the result Manufacturer Published Runtime. Loads between published figures are labeled Estimated from Manufacturer Data, and loads outside the published range are labeled Extrapolated with a wider range. Those are GeneratorRuntime estimates, not Generac specifications.
Operate it safely
Like every portable generator, the Generac GP6500 must be operated according to the manufacturer's safety instructions: outdoors only, well away from doors, windows, and vents, with battery CO alarms inside your home. A CO shutoff feature is not a substitute for safe placement. Never refuel while the engine is running or hot.
Generac GP6500 FAQ
›How long will a Generac GP6500 run on a full tank?
Generac's spec sheet for the COsense models lists 16.5 hours at 25% load and 11.5 hours at 50% load on the 7.9-gallon tank.
›What is the Generac GP6500 runtime at full load?
Generac does not publish a full-load runtime. The calculator extrapolates beyond 50% load and labels those results "Extrapolated" with a wider range.
›How many watts does the Generac GP6500 produce?
6,500 watts running and 8,125 watts starting, according to Generac.
›Which GP6500 models does this page cover?
The GP6500 with COsense: models 7680-1 / 7680-2 (49-state) and 7683-1 / 7683-2 (50-state). Older GP6500 and GP6500E versions with a 6.9-gallon tank and a 10.5-hour runtime at 50% load are different configurations and are not covered here.
Similar generators
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- Honda EB6500 — 5,500 watts running
- Generac GP7500E Dual Fuel with COsense (8011-2) — 7,500 watts running
- Generac GP8000E with COsense (EFI) (8929) — 8,000 watts running
Browse the full Generator Runtime Database or use the main Generator Runtime Calculator.