If you’ve ever wandered around a farm grain storage facility, a feed mill, or maybe even a big commercial ethanol plant, you’ve probably seen silo sweep augers at work—those twisty metal screws that pull grain out of the bottom of a silo so you don’t have to climb in and shovel by hand. And if you’ve ever been in the market for one, you might’ve stopped mid-search and thought, “Wait, are these things actually different sizes?” Spoiler: Yeah, they are. And picking the wrong size isn’t just an annoyance—it can cost you time, grain, and even money. As a silo sweep auger supplier who’s talked to hundreds of farmers and plant managers over the last 12 years, I’ve seen way too many people skip checking sizes and end up with a machine that doesn’t fit their silo. Let’s break this down like we’re chatting over a coffee (no stuffy jargon, promise). Silo Sweep Auger
First off, why does size even matter here? It’s not like you can just grab a random auger and shove it in a silo—these things have to work with the silo’s layout, the grain you’re storing, and how often you need to empty it. The biggest size people mess up is the diameter of the auger itself, right? That’s the big metal screw part. Let’s start with small-scale setups, like family farms with 1,000-bushel silos. Those are usually the round, metal ones you see on most small operations, maybe 12 to 18 feet in diameter. For those, we sell augers with 6-inch diameters. Wait, 6 inches? Yeah, that makes sense—smaller silos don’t need a giant screw to move grain. A 6-inch auger fits perfectly in the center discharge tube of a small silo, moves about 10 to 15 tons of grain an hour, and it’s light enough that one person can install it in 30 minutes without needing a crane. I remember a guy from Iowa last year who bought a used auger online and tried to cram an 8-inch one into his 14-foot silo. It didn’t fit the discharge, and the motor was too weak to turn it—he had to pay a welder to cut a new discharge and a electrician to upgrade his power, costing him almost $2,000. Ouch.
Now move up to medium-scale operations, like 5,000 to 20,000 bushel silos, which are 20 to 30 feet in diameter. For these, we use 8 to 10 inch augers. The bigger diameter moves more grain—like 25 to 40 tons an hour—which is key if you’re processing grain weekly, not just once a season. But here’s a thing I bet you didn’t know: it’s not just the auger diameter. The length matters too. A 20-foot diameter silo’s sweep auger needs to extend all the way from the center discharge to the silo wall, right? Because you want to push every last kernel of grain off the wall so you don’t leave a bunch that goes bad or gets wasted. If you buy an auger that’s too short, it’ll leave a 2 to 3 foot patch of grain stuck to the wall. That’s not just lost product—if you’re storing corn, that leftover grain can get moldy over winter and contaminate the next load. I had a feed mill manager from Illinois tell me that once—he bought a cheap auger from a guy at a farm show that was 2 feet too short, and he ended up with 200 bushels of moldy corn that he had to sell for half price as animal feed. Lesson there: measure your silo’s inner diameter twice before ordering. Don’t guess. That’s the biggest mistake people make.
Then there’s the big league stuff: commercial grain elevators, ethanol plants, or farms with silos over 30 feet in diameter, holding 50,000 bushels or more. For those, we’re talking 12 to 18 inch augers, and some even have multiple sweep augers working together. Wait, multiple? Yeah, because a 40-foot diameter silo is huge. One single 18-inch auger would have to be so big and heavy that you’d need a crane just to install it, and the motor to turn it would be like the size of a small car. Instead, a lot of big operations use two or three smaller augers that run in a loop at the bottom of the silo, moving grain to a central pickup point. I worked with an ethanol plant in Indiana a couple years ago that had four 16-foot diameter silos for storing corn, and they were having issues with their old auger leaving grain in the corners. We swapped them out for 14-inch sweep augers with a reinforced flight design (that’s the spiral part) and adjusted their speed. They went from emptying each silo in 12 hours to 7 hours, and lost less than 0.5% of grain instead of the 2% they were before. That’s a big deal when you’re moving thousands of tons a year.
But wait, size isn’t just about the metal auger and its length. There are other size factors that people sleep on. Like the motor size. A 6-inch auger needs a 1.5 horsepower motor, right? But an 10-inch auger needs 5 horsepower, and a 16-inch one needs 15 or more. If you hook a 10-inch auger up to a 1.5 hp motor, it’ll burn out in a week, because it’s too much weight for the motor to turn. That’s why you’ll see some augers labeled as “matched systems”—we test every size to make sure the motor, the auger, and the gearbox all work together, so you don’t have to guess. Another size thing: the clearance between the auger and the silo wall. If the auger’s flight is too long, it’ll scrape the concrete or metal wall, which wears out both the auger and the silo over time. If it’s too short, it leaves grain. We design our augers so the clearance is 1/8 to 1/4 of an inch, which is the sweet spot for almost all silos.
Also, what grain are you storing? That changes the size you need too. If you’re storing light, fluffy stuff like soybeans or rice, you can go with a slightly smaller auger diameter, because those grains flow easier. But if you’re storing heavy, dense stuff like hard red wheat or corn that’s been dried to low moisture, you need a bigger auger, because it can move more weight without jamming. I had a farmer from Ohio who was storing soybeans in his 25-foot silo, and he bought a 8-inch auger, which he thought was right. But when he switched to storing corn, that 8-inch auger would jam every time it got to the wall. We swapped him to a 10-inch auger, and problem solved. That’s another thing to consider—don’t just buy for the grain you have now, but the grain you might store in the future. No one wants to have to buy a new auger two years down the line.
Now, let’s talk about common myths, because there’s a lot of bad info out there about auger sizes. First myth: “Bigger is always better.” Yeah, no. A big auger costs more to buy, uses more electricity, and if you put it in a small silo, it’s overkill. I had a guy last year who tried to put a 12-inch auger in a 15-foot silo. It cost him $1,200 more than a 6-inch, and he was paying $50 more a month in electricity, just so he could empty his silo an hour faster. Not worth it. Another myth: “All sweep augers are one-size-fits-all for silo type.” Wait, what kind of silo do you have? There’s flat-bottom silos, hopper-bottom silos, even big steel bins that look like silos. Hopper-bottom silos have a sloped bottom, so the sweep auger is shorter, because it only has to reach from the center to the slope. Flat-bottom silos have a flat floor, so the auger has to extend all the way to the wall, so it’s longer. If you take a hopper-bottom auger and put it in a flat-bottom silo, it won’t reach the wall, and you’ll leave grain. That’s a huge mistake I see all the time.
As someone who’s been in this game for years, I’ll be straight with you: sizing your silo sweep auger isn’t hard, but you can’t guess. Let’s recap the basics so you don’t mess up: First, measure your silo’s inner diameter—from one wall to the other, straight across. Second, note if it’s hopper-bottom or flat-bottom. Third, write down what grain you store, and how much of it you need to move per hour. If you’re a small family farm with a 14-foot hopper-bottom silo for soybeans, you need a 6-inch, short auger. If you’re a medium feed mill with a 28-foot flat-bottom silo for corn, you need an 10-inch, long auger. If you’re a big grain elevator with 40-foot silos, you need 14 to 16 inch augers, maybe a pair per silo.
At the end of the day, the right size auger makes your life way easier. No more shoveling leftover grain, no more burnt motors, no more wasted money on grain that goes bad because you left it in the silo. If you’re not sure what size you need, or you want to ask about different sizes for your specific setup, reach out to chat. We don’t push you to buy the biggest or most expensive one—we’ll help you pick exactly what fits your silo, your grain, and your budget. Don’t waste another season fighting with an auger that doesn’t work for you. Let’s make this work right.
If you need more details on sizing, performance, or custom options, connect with us to discuss your silo sweep auger needs.
Sweeps and Unloads References
- National Agricultural Statistics Service. 2022. Grain Storage Facilities and Practices in the U.S. Agricultural Management Survey.
- ASABE Standards. 2021. Design and Safety for Agricultural Augers (S341).
- Grain Elevator and Processing Society. 2020. Modern Silo Equipment Best Practices.
- University of Illinois Extension. 2019. Silo Emptying Systems for Mid-Scale Grain Operations.
Liaoning Hongrui Technology Development Co., Ltd.
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