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The distinction this entire page turns on. A storage cover is a bag that goes over a switched-off, cooled-down generator. A running cover is an open-sided tent that keeps rain off the top while leaving all four sides completely clear. Putting a storage cover, a tarp, a box or any enclosure over a running generator traps exhaust — and exhaust is where the carbon monoxide is. The US Consumer Product Safety Commission states one portable generator can emit as much carbon monoxide as hundreds of cars and links more than 100 US deaths a year to generator CO. It is colorless and odorless, so nothing warns you. Source: CPSC Carbon Monoxide Information Center.
A generator cover is a $25 defense against a several-hundred-dollar problem, and almost all the disappointment in the category comes from two mistakes. The first is buying the wrong type — a storage bag when what was needed was a running canopy, or the reverse. The second is measuring the frame and forgetting the handle. Get those two right and this is one of the least complicated purchases you will make.
Top Picks at a Glance
Storage Cover or Running Cover?
| Storage cover | Running cover / tent | |
|---|---|---|
| Shape | Fitted bag, closed on all sides | Open-sided canopy on a frame |
| Use with engine running | Never | Yes — that is its purpose |
| Protects against | Rain, dust, UV, workshop debris | Rain and snow falling on the machine |
| Typical price | $20–$35 | $45–$90 |
| Wind performance | Drawstring hem; can lift if loose | Needs staking or tying down |
| What it does not do | Anything while the engine is on | Make flooding or 20-foot placement rules optional |
If your generator lives in a dry garage and only runs in fair weather, a storage cover is all you need. If you live somewhere that outages arrive with the storm — which is most of the United States — you want both: a bag for the eleven and a half months it sits, and a canopy for the day it earns its keep.
Our #1 Pick: Porch Shield 32 x 24 x 24
Porch Shield dominates this category, and the mid-size 32 x 24 x 24 cover is the one that fits the greatest number of American home backup generators — roughly the 5,000 to 10,000 watt band where most households end up.
The construction is unremarkable in the best way: 600D polyester with a waterproof coating, taped or double-stitched seams, and an elastic hem with a drawstring. The drawstring is the detail that matters. A cover that merely rests on a generator becomes a sail in the first real wind and ends up in a neighbor's yard; one that cinches under the frame stays put.
What the enormous owner-review record makes clear is that fit complaints, not durability complaints, dominate the negative reviews — and almost all of them come from measuring the frame rather than the machine as it actually stands. Measure with the handle folded down where you keep it and the wheels on, then add two to three inches in every direction. Do that and the review record on this cover is genuinely excellent across several seasons of outdoor exposure.
The limitation is absolute and worth repeating: this is a storage cover. It goes on a generator that is switched off and cool, and it never goes on one that is running.
Check price on Amazon → (paid link)
The Ranked Field
Best for storage protection on a mid-size portable generator
- 32 x 24 x 24 inches, sized for 5,000–10,000 watt units
- 600D heavy-duty polyester with a waterproof coating
- Elastic hem with a drawstring to stop it lifting in wind
- Storage cover only — the machine must be switched off and cool
Why buy it: the most-owned generator cover in the US by a wide margin, which is why the fit notes in its review record are unusually reliable — measure before ordering and it works.
Best for 9,500 to 14,500 watt home backup units with wheel kits
- 38 x 28 x 30 inches for large open-frame generators
- Same 600D waterproof fabric as the smaller sizes
- Deep enough to clear a handle bar and wheel kit
- Storage cover only
Why buy it: the size most large home backup generators actually need — buyers routinely order the mid-size and discover the handle bar adds six inches nobody accounted for.
Best for inverter generators and small portables
- 26 x 20 x 20 inches for compact and inverter units
- Waterproof 600D polyester with a drawstring hem
- Packs down small enough to live in the generator case
- Storage cover only
Why buy it: a snug fit matters more on small units than large ones, because a loose cover on a light generator becomes a sail in the first real storm.
Best for keeping rain off a generator that has to run through a storm
- Open-sided tent design that leaves all four sides clear for airflow
- Fits most 3,500–12,000 watt open-frame generators
- Heavy-duty waterproof fabric with a frame and tie-downs
- Designed specifically for use with the engine running
Why buy it: the open-sided design is the entire point — it is a roof, not an enclosure, and that distinction is the difference between rain protection and a carbon monoxide trap.
Best for Champion generators, where the dimensions are already matched
- Cut to fit Champion 4,800–11,500 watt portables
- Weather-resistant vinyl-backed fabric
- Elastic hem and reinforced seams
- Storage cover only
Why buy it: a cover cut for the actual machine sits tighter and lasts longer than a universal one, and on a windy site that tightness is what stops the fabric abrading itself to death.
Best for the Westinghouse WGen home backup range
- Sized around the Westinghouse WGen portable range
- Water-resistant coated fabric with an elasticized hem
- Cut to clear the fold-down handle
- Storage cover only
Why buy it: if you already own a WGen unit this removes the measuring problem entirely, which is where most generator cover disappointment starts.
Quick Comparison
| Product | Best for | Rating | Price | Buy |
|---|---|---|---|---|
| Porch Shield Waterproof Universal Generator Cover, 32 x 24 x 24 inch, for Generators 5000–10000 Watts | Best Overall | — | Check (paid link) | |
| Porch Shield Waterproof Universal Generator Cover, 38 x 28 x 30 inch, for Generators 5500–15000 Watts | Best for Large Generators | — | Check (paid link) | |
| Porch Shield Waterproof Universal Generator Cover, 26 x 20 x 20 inch, for Generators 3000–5000 Watts | Best Small | — | Check (paid link) | |
| IGAN Generator Cover While Running, Ultra Heavy Duty Tent for 3500–12000 Watt Generators | Best Running Cover | — | Check (paid link) | |
| Champion Power Equipment Weather-Resistant Storage Cover for 4800–11500 Watt Portable Generators | Best Branded Fit | — | Check (paid link) | |
| Westinghouse WGen Generator Cover, Universal Fit for Portable Generators | Best for Westinghouse Units | — | Check (paid link) |
Sizing, Without the Return
Measure three dimensions with the generator standing as it normally does — wheels fitted, handle in its resting position, fuel cap on. Add two to three inches to each. That allowance covers the drape and lets the drawstring pull under the frame rather than straining at the corners.
| Generator size | Typical cover | Watch out for |
|---|---|---|
| 2,000–3,500W inverter | 26 x 20 x 20 in | Fold-down handles that add height |
| 3,500–5,000W portable | 26 x 20 x 20 or 32 x 24 x 24 in | Wheel kits that widen the base |
| 5,000–10,000W open frame | 32 x 24 x 24 in | Lifting bars over the engine |
| 9,500–15,000W home backup | 38 x 28 x 30 in | Tall handle bars, 12-inch wheels |
| Any unit stored with fuel cans nearby | — | Cover the generator, never the cans |
How We Rank
We do not buy or physically handle these covers. Rankings come from aggregated owner ratings across the most-owned generator covers, weighted toward reviews written after a full season of outdoor exposure where fabric failure, seam leaks and UV degradation appear, and cross-checked against published dimensions and fabric specifications. Four things carry the weight: whether the product is honest about running versus storage use, which we treat as a safety criterion rather than a feature; real waterproofing rather than water resistance; hem and drawstring design, since wind is what destroys most covers; and dimensional accuracy in the owner record. Prices were checked at the time of writing. Full method: how we rank.
What Owners Actually Complain About
Wrong size. The overwhelming majority of low ratings. Almost always a handle or a wheel kit that was not measured.
Wind lift. Covers without a proper drawstring or tie-downs leave the generator during storms. Cinch it under the frame, or add a bungee.
Water-resistant sold as waterproof. Lighter fabrics shed a shower and wet through in a day of steady rain. For a generator stored fully outdoors, buy the heavier 600D-plus fabric.
Condensation underneath. A fully waterproof cover on a machine stored on damp ground can trap moisture against it. Store off a concrete slab, on a pallet or shelf, and take the cover off periodically to air.
Running covers assumed to be optional shelter. A canopy does not change where the generator may be placed. Twenty feet from the house, exhaust pointed away, still applies.
The Verdict
For most households the Porch Shield 32 x 24 x 24 is the right storage cover — proven fabric, a hem that stays put, and the size that fits the widest range of home backup generators. Step up to the 38 x 28 x 30 for a 9,500 watt-plus machine, and if you already own a Champion or a Westinghouse, take the matched cover and skip the measuring altogether. If your outages arrive with weather, add the IGAN running cover — but understand exactly what it is: an open-sided roof, not an enclosure. Never cover a running generator with anything closed, and never run one anywhere but outdoors, at least 20 feet from the house, with the exhaust pointed away. Check price on Amazon → (paid link)
Sources: US Consumer Product Safety Commission Carbon Monoxide Information Center; ESFI portable generator safety.
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