Auger Length Calculator
Buy an auger too short and it cannot reach the bin; buy too long and you paid for steel you never use. The right length is the straight-line distance from the intake to the bin’s fill point, plus a margin for the discharge spout and setup clearance.
The Auger Length Calculator below computes that distance from your vertical lift and horizontal reach using the Pythagorean theorem, adds your safety margin, and recommends the nearest standard auger size, so you can quote and order with confidence.
Quick Answer
Key takeaways
- The auger is the hypotenuse of the lift and reach triangle: sqrt(lift² + reach²).
- Measure lift to the fill point (peak ring or eave), not just the bin wall.
- Add 5% margin for the discharge spout and setup clearance, then round up to a manufactured size.
- Steeper angles move grain slower per horsepower; capacity charts assume typical 30-45 degree operation.
Measuring lift and reach correctly
Two measurement mistakes cause most sizing errors. Lift is measured from the intake hopper to the fill point, the peak ring or roof hatch where grain enters, and must include any foundation or hopper height. Reach is the ground distance from the intake to directly below that fill point, not to the bin wall.
| Bin example | Eave height | Peak height | Typical lift |
|---|---|---|---|
| 24 ft dia, 6 rings | 22 ft | 29.3 ft | 30-32 ft |
| 36 ft dia, 8 rings | 29.4 ft | 42.3 ft | 43-45 ft |
| 48 ft dia, 9 rings | 33 ft | 47.7 ft | 48-50 ft |
Peak heights run well above eave heights on wide bins, which is why measuring to the fill point matters: a 48 ft bin can need 15 ft more lift than its eave suggests.
Worked example, checked against this exact tool
Enter the pre-filled defaults and click Calculate. Filling a mid-size bin:
| Item | Value |
|---|---|
| Vertical lift | 20 ft |
| Horizontal reach | 30 ft |
| Straight-line distance | √(400 + 900) = 36.06 ft |
| Safety margin | 5% → 1.80 ft |
| Required length | 37.86 ft |
| Buy | 41 ft (next standard size) |
| Operating angle | 33.7° |
What drives the size
What competing calculators miss
Existing auger calculators do the hypotenuse math and stop. This one finishes the buying decision:
No standard-size recommendation. A computed 37.86 ft is not a product you can buy. Ours maps to the next manufactured size (41 ft) in feet or meters.
No operating angle. Angle affects capacity per horsepower and whether the discharge clears the bin. Ours reports it.
No fill-point guidance. Competitors say “enter height” without explaining eave versus peak. Our bin table shows why the distinction costs or saves real feet.
Frequently asked questions
Most farm augers operate between 30 and 45 degrees. Capacity charts from manufacturers and dealers are published at these incline angles; steeper angles reduce throughput for the same horsepower, so an angle far above 45 degrees may need a larger tube or motor.
To the fill point where grain enters, usually the peak ring or roof hatch. On wide bins the peak can be 10-15 ft above the eave, so measuring only to the eave undersizes the auger badly.
Common farm auger lengths run 31 to 91+ ft in roughly 10 ft steps (31, 41, 51, 61, 71, 81), with tube diameters of 8, 10, 13, and 16 inches. Always round the computed length up to the next available size.
Length itself is secondary; horsepower is driven by tube diameter, lift height, and throughput. That said, longer augers at steep angles do demand more power, and manufacturers publish recommended horsepower (often 40-175 HP) per model.
Yes if positioned between them, but size for the worst case: the tallest bin and the longest reach, each with margin. Swing-away hopper augers are designed for repositioning between bins.
The discharge spout extends past the tube end, ground is rarely level, and the intake sits back from the grain source. Five percent covers these without paying for a full size jump; the final step rounds up to a manufactured size anyway.
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References
- Oklahoma State University Extension, “Auger Conveyors” fact sheet – auger length driven by bin placement and height; diameter, pitch, and motor power drive capacity. OSU Extension: Auger Conveyors. Accessed October 19, 2026.
- University of Wisconsin-Madison Dairyland Initiative, “Augers and Bins” – auger sizing, common diameters (4-10 in), and length dependence on bin placement. Dairyland Initiative: Augers and Bins. Accessed October 19, 2026.
- Ernewein Farm Equipment, “Auger Length Chart” (PDF) – required auger length by bin model at 30-45 degree incline angles. Auger Length Chart (PDF). Accessed October 19, 2026.
- Farmers Hotline, “Augers That Fit the Farm” – manufacturer length ranges (50-114 ft) and diameter options for major brands. Farmers Hotline: Grain Augers. Accessed October 19, 2026.
- Penn State Extension, “Grain Auger Safety” – entanglement and engulfment hazards, guarding, and lockout practices. Penn State: Grain Auger Safety. Accessed October 19, 2026.