Pier Footing Size Calculator

Last updated: 07 Aug 2025 | Author: Brij | Review By: Irshad

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Use our Pier Footing Size Calculator to determine the required footing diameter and depth based on load, soil bearing capacity, and safety factors. Ensure safe and code-compliant construction with this easy tool.

Load on Each Pier:

Soil Bearing Capacity:

Footing Shape:

Pier Diameter:

Safety Factor:

Footing Design Results

Required Footing Area:

sq.ft

Recommended Footing Diameter:

Recommended Footing Width:

Recommended Thickness:

Actual Bearing Pressure:

psf

What is a pier footing?

A pier footing is a type of deep foundation that supports vertical loads from a structure. It transfers the weight directly to the ground beneath through vertical columns (piers), often used in decks, sheds, cabins, and light structures.

Formulas Used

1. Footing Area

The basic footing area is calculated by:

$\text{Area} = \frac{\text{Load}}{\left(\frac{\text{Soil Bearing Capacity}}{\text{Safety Factor}}\right)}$

2. Diameter of Circular Footing

Once the area is known, for a circular footing:

$\text{Diameter} = 2 \times \sqrt{\frac{\text{Area}}{\pi}}$

3. Side of Square Footing

$\text{Side} = \sqrt{\text{Area}}$

4. Minimum Depth or Thickness of Footing

Depth is often taken as:

$\text{Depth} = \text{Diameter} \times 0.5$

Example

Let’s say you have:

Load = 6,000 lbs
Soil Bearing Capacity = 2,000 psf
Safety Factor = 1.5
Footing Shape = Circular

Step 1: Calculate Area

$\text{Area} = \frac{6000}{\frac{2000}{1.5}} = \frac{6000}{1333.33} \approx 4.5 \, \text{sq ft}$

Step 2: Calculate Diameter

$\text{Diameter} = 2 \times \sqrt{\frac{4.5}{\pi}} \approx 2 \times \sqrt{1.433} \approx 2 \times 1.197 = 2.39 \, \text{ft}$

Step 3: Minimum Depth

$\text{Depth} = 2.39 \times 0.5 = 1.2 \, \text{ft}$

Conclusion

This calculator provides a quick way to determine the ideal pier footing size for safe structural support. Always follow your local building codes and consult with an engineer for critical structures.

FAQs

Where are pier footings commonly used?

Pier footings are commonly used in:

Decks and porches
Pole barns and small cabins
Sloped or uneven terrain
Areas where full concrete foundations are not practical or cost-effective

What is the difference between a pier and a regular footing?

A pier is a vertical structural element that supports a point load, while a regular (spread) footing distributes the load over a wider area under walls or columns. Piers go deeper into the ground and are spaced apart, unlike continuous strip or slab footings.

How deep should a pier footing be?

The depth of a pier footing depends on:

Local frost line depth
Soil conditions
Load requirements
It should always extend below the frost line to prevent movement due to freeze-thaw cycles.

Check out 1 similar Pier Footing Size Calculator :

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