Grain Auger Length Calculator: How to Measure

This grain auger length calculator works out the minimum tube length you need to reach from the grain bin outlet to the top of the pile or target height. You enter the horizontal distance from the bin to the discharge point and the vertical height you need to lift the grain, and the calculator returns the required auger length in the same unit you used (feet or meters). It also shows the angle of elevation, which helps you check whether the auger will operate within a safe and efficient range.

Formula

The required auger length is the straight-line distance from the lower end (where grain enters) to the upper end (where grain discharges). That distance is the hypotenuse of a right triangle formed by the horizontal run and the vertical lift:

L = √(H² + V²)

Where:

• L = auger tube length (same unit as H and V, typically feet or meters)
• H = horizontal distance from the auger inlet to the point directly below the discharge outlet
• V = vertical height from the auger inlet to the discharge point

The angle of elevation is:

θ = atan(V / H)

This angle matters because most grain augers are designed to operate between roughly 30° and 45°. At lower angles, grain may not flow well; at higher angles, you may need more power and the capacity drops.

Worked Example

Using the default values from the calculator: horizontal distance H = 50 ft, vertical lift V = 15 ft.

Step 1: Square both values.

H² = 50² = 2500
V² = 15² = 225

Step 2: Add them.

2500 + 225 = 2725

Step 3: Take the square root.

√2725 ≈ 52.2 ft

So the auger tube should be at least 52.2 feet long. The angle of elevation is atan(15/50) = atan(0.3) ≈ 16.7°. That is quite shallow; in practice you would likely need a longer auger or a different setup to get a steeper angle.

Why the Angle Matters

The calculator gives the minimum length for a given height and horizontal reach, but real auger selection is not just about the triangle. The angle of the auger affects how much grain it can move per hour. At a shallow angle, grain tumbles back down and capacity drops. At a steep angle, the auger has to lift grain higher against gravity, which also reduces capacity and increases power requirements. Most manufacturers publish capacity charts for their augers at specific angles, usually 30°, 35°, 40°, and 45°. You should check those charts with the angle from this calculator to see if the auger you are considering will deliver the bushels per hour you need.

How to Measure H and V Correctly

The accuracy of the result depends entirely on your two measurements. Here are the common pitfalls:

• Measure to the discharge point, not the bin wall. If you are filling a bin from the top, the discharge end of the auger must reach over the bin wall or the pile peak. Measure to that point, not just to the edge of the bin.
• Include the height of the support. The vertical lift is from the inlet (usually on the ground or on a hopper) to the discharge end. If the auger is mounted on a stand or a hopper, include that height.
• Use the same unit for both measurements. If you measure horizontal in feet and vertical in inches, convert one before entering. The calculator assumes both are in the same unit.
• Account for the slope of the ground. If the ground between the inlet and the bin is not level, the vertical lift is not simply the height of the bin. You need the actual vertical difference between the inlet and discharge points.

Common Mistakes and Misconceptions

A frequent mistake is using the horizontal distance from the bin to the base of the bin, not to the discharge point. For example, if the bin is 30 feet in diameter and you want to discharge over the center, the horizontal distance is not 30 feet but 15 feet (from the edge to the center). Another misconception is that a longer auger always works better. A longer auger is heavier, more expensive, and may require more horsepower to turn. The correct length is the one that reaches with a safe angle, not the longest one available.

Also, the angle from the calculator is the geometric angle. The actual auger angle may be slightly different because the inlet end is often raised off the ground on a hopper or a stand. Always measure from the actual inlet position, not from the ground directly below the discharge point.

Safety and Operational Considerations

Grain augers are dangerous machines. The rotating flighting and the intake area can pull in clothing, limbs, or tools. Do not use this calculator as a substitute for reading the manufacturer’s manual. Always:

• Keep guards and shields in place.
• Never reach into the auger while it is running.
• Lock out power before clearing jams.
• Stay away from the intake when the auger is operating.
• Ensure the auger is properly supported and anchored, especially at steep angles.

Also consider the weight and balance. A long auger may need a support stand or a winch to raise and lower safely. The angle you calculate is also the angle you set the auger to; if that angle is too shallow, grain may not flow, and if too steep, the auger may be unstable.

Alternatives to a Single Straight Auger

If your required length or angle is outside the practical range, you have alternatives:

• Use a longer auger at a steeper angle. Sometimes you can move the inlet closer to the bin to reduce the horizontal distance, which increases the angle.
• Use a vertical auger or bucket elevator. For very high lifts, a vertical auger or a bucket elevator may be more efficient.
• Add a second auger or a transfer hopper. If the distance is too great, you can use two augers in series, but that adds cost and complexity.
• Use a grain thrower or blower. For filling bins from a distance, a pneumatic system might be an option, though it is more expensive.

Frequently Asked Questions

How do I know what angle my auger is?

You can measure the angle with a digital inclinometer or a smartphone app. Alternatively, measure the horizontal distance from the base of the auger to the point directly below the discharge end, and the vertical height from the base to the discharge end. Then use the formula θ = atan(V/H). Most augers have a recommended operating range printed in the manual.

Can I use this calculator for a bin that is not round?

Yes, the shape of the bin does not matter. You only need the horizontal distance from the auger inlet to the discharge point and the vertical lift. For a rectangular bin, measure to the point where you want the grain to land.

What if my horizontal distance is zero?

If the horizontal distance is zero, the auger is vertical. The required length is simply the vertical lift. The angle would be 90°, which is usually too steep for a standard grain auger; you would need a vertical auger or a bucket elevator.

Does the length include the intake and discharge sections?

No, the length from the calculator is the straight-line distance between the two ends. The actual auger tube length may need to be longer if the intake and discharge spouts extend beyond the tube. Check the manufacturer’s specification for the overall length including those sections.

How much does a grain auger cost?

Prices vary widely by length, diameter, and features. As of recent years, a 10-inch diameter auger in the 50-70 foot range can cost several thousand dollars, but you should get quotes from local dealers. The calculator helps you determine the length you need, which is the first step in getting an accurate price.

Can I use this for moving grain from a truck to a bin?

Yes, the same geometry applies. Measure from the truck’s discharge point (where grain leaves the truck) to the bin’s inlet, and the height difference between those points. The calculator gives the minimum auger length for that setup.

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in h | Horizontal distance | ft | 50 | 0
in v | Vertical lift | ft | 15 | 0
out length | Auger length | ft | sqrt(h^2 + v^2) | 1
out angle | Angle of elevation | deg | atand(v / h) | 1