Imperial units
Enter Pole and Load Data
Use measured values and project-specific allowable stresses. This tool evaluates a simplified cantilever model above grade.
Example Data Table
These figures demonstrate data entry only. They are not approved design values.
| Example case | Exposed height | Butt diameter | Point load | Point height | Uniform load | Axial load |
|---|---|---|---|---|---|---|
| Equipment support pole | 30 ft | 14 in | 450 lb | 28 ft | 15 lb/ft | 900 lb |
| Sign support pole | 20 ft | 12 in | 260 lb | 16 ft | 10 lb/ft | 350 lb |
Formula Used
The calculator uses an exposed, fixed-base cantilever approximation. Loads are multiplied before stress checks.
In the deflection equation, dimensions use inches and uniform load converts to pounds per inch. The interaction index is fb/Fb + fc/Fc. It is a screen, not a complete code interaction equation.
How to Use This Calculator
- Measure exposed height from finished grade to the pole top.
- Measure butt diameter at grade. Enter the tip diameter for taper reporting.
- Enter each lateral load and its location. Use uniform load for distributed demand.
- Enter axial compression separately. Do not enter uplift as compression.
- Use verified allowable stresses and stiffness from project documentation.
- Select a load multiplier that matches your calculation basis.
- Review moment, shear, stress ratios, deflection, and the warning statement.
- Have a qualified professional check soil, connections, adjustment factors, and code requirements.
Wood Pole Loading Guidance
Wood poles carry lateral forces from wind, equipment, cables, signs, and temporary attachments. The critical zone is often near grade. This calculator treats the exposed pole as a cantilever. It estimates actions at the groundline. It does not model soil resistance, foundation rotation, decay, knots, or connection failures.
Understand the Load Path
A point load creates shear and a bending moment. Its height matters greatly. A small force near the top can produce a large moment. A uniform load represents distributed wind or continuous attached weight. The calculator combines both loads at the groundline. It also accepts an axial load. Axial load produces compressive stress at the butt section.
Use Reliable Pole Properties
Enter the actual butt diameter at groundline. Round poles resist bending through their circular section modulus. Small diameter changes have a strong effect. Measure poles after allowing for taper, weathering, and suspected decay. Use verified allowable stresses for the selected species, treatment, grade, moisture condition, and service environment. Do not substitute generic values for a designed project.
Read the Screening Results
The bending ratio compares calculated bending stress with your entered allowable bending stress. The shear ratio does the same for transverse shear. The compression ratio compares axial stress with the entered compression value. The interaction index adds bending and compression ratios. It is a conservative screening display only. It is not a complete wood-design interaction equation or a code approval.
Deflection and Stability
Excessive deflection can damage conductors, signage, equipment, and adjacent structures. The displayed tip deflection uses a base-section stiffness approximation. Taper normally changes stiffness along the pole. Connection movement and soil movement can add more deflection. The embedment ratio is reported for reference. It does not prove adequate foundation capacity. A pole can have acceptable wood stress yet fail through inadequate soil support.
Design Review Matters
Check governing wind, ice, seismic, impact, construction, and maintenance cases. Consider load combinations, duration factors, strength adjustments, fastener capacity, utility clearances, and local rules. Inspect poles for rot, splits, checks, insect damage, and groundline deterioration. Use measured conditions when modifying existing poles. Have a qualified engineer review final dimensions, loads, embedment, and connections before construction or field changes. Document every input, inspection finding, assumption, and revision for traceability during later maintenance decisions and reviews.
Frequently Asked Questions
1. Does this calculator replace an engineer?
No. It provides preliminary screening only. A qualified professional must verify loads, wood properties, adjustment factors, soil support, foundations, connections, clearances, and governing regulations.
2. Which diameter should I enter?
Enter the measured outside butt diameter at groundline. The program uses that circular section for base bending, shear, compression, and simplified stiffness calculations.
3. Can I use this for a utility pole?
Use it only as an early review tool. Utility poles require project-specific loading, attachment geometry, conductor effects, clearances, foundation assessment, and the applicable utility or jurisdictional criteria.
4. Why does point-load height matter?
Groundline moment equals force times lever arm. The same lateral force causes much more bending when it acts near the pole top.
5. What does uniform lateral load represent?
It represents a load spread along the exposed height. It may approximate wind demand, attached cable demand, or another distributed lateral action after proper engineering determination.
6. Does embedment depth prove soil capacity?
No. The embedment ratio is informational. Soil type, groundwater, compaction, pole movement, lateral resistance, and local requirements must be checked separately.
7. Are the default stress values approved design values?
No. They are editable placeholders for demonstration. Enter verified values that reflect the actual wood species, grade, treatment, condition, moisture, duration, and relevant adjustments.
8. How is tip deflection estimated?
The tool combines standard cantilever deflection equations using the butt-section moment of inertia. Taper, soil rotation, connection slip, and localized damage can change real movement.
9. Does it check bolts and attachments?
No. Check each bolt, bracket, guy, connection, reinforcement, and attached component separately. Their forces may govern the final design.
10. Why use a load multiplier?
It lets you screen another load level without re-entering every force. Select the multiplier only after confirming your governing design method and load basis.
11. What should I inspect before reusing a pole?
Inspect for decay, rot, splits, checks, insect damage, surface loss, groundline deterioration, prior holes, hardware damage, and excessive lean. Use measured remaining section properties.