How to Use This Footing Estimate

A quick sequence to estimate and place concrete for this footing:

1. Confirm hole dimensions are 14" × 14" × 36" after excavation.
2. Convert inches to feet (14" = 1.1667 ft, 36" = 3 ft) and calculate volume in cubic feet.
3. Add a waste allowance (10% used here) to get the planning volume.
4. Decide between bags or ready-mix and either buy the required number of bags or order the closest practical readymix amount.
5. Set reinforcement if required, place concrete, consolidate, and finish the top to the required elevation.

Formula

Volume for a rectangular/square footing equals length × width × depth, all in feet. Convert inches to feet by dividing by 12 before multiplying.

For this footing: length = 14" = 1.1667 ft, width = 14" = 1.1667 ft, depth = 36" = 3 ft. Multiply: 1.1667 × 1.1667 × 3 = 4.0833 cubic feet.

To convert cubic feet to cubic yards, divide by 27: 4.0833 ÷ 27 = 0.1512 cubic yards. Add 10% waste: 4.0833 × 1.10 = 4.4916 cu ft, which is 0.1663 yd³.

Worked Example

Single-footing example: one 14" × 14" × 36" footing needs 4.0833 cu ft of concrete (0.1512 yd³). Including 10% waste, plan for 4.4916 cu ft (0.1663 yd³); that works out to about 15 40-lb bags, 10 60-lb bags, or 8 80-lb bags.

Multiple-footing example: three identical footings require 3 × 4.0833 = 12.2499 cu ft total, which is 0.4537 yd³. With 10% waste plan 13.4749 cu ft (0.4981 yd³). For bags, multiply the per-footing planning counts: 45 40-lb bags, 30 60-lb bags, or 24 80-lb bags.

Bag Count Estimate

• 8 bags of 80 lb concrete mix
• 10 bags of 60 lb concrete mix
• 15 bags of 40 lb concrete mix

Always verify the actual yield on the product label before buying materials.

When Bagged Concrete vs Ready-Mix Makes Sense

For a single 14" × 14" × 36" footing the planning volume is only 0.1663 cubic yards. That’s well below most ready-mix minimums, so bagged concrete is often the practical choice for one or two footings. Bagged concrete lets you buy the precise amount and avoids ordering a whole yard or more of ready-mix.

That said, ready-mix has advantages if you have many footings or limited labor: it reduces mixing time, gives consistent slump, and speeds placement. If you go ready-mix, compare the smallest supplier minimum and account for the extra concrete and cost. For this size, bagged concrete requires roughly 15 40-lb bags (per footing planning volume) versus a fractional yard delivery if you need exact volume control.

Common Uses for This Footing Size

A 14x14x36 footing is commonly used for supporting single posts in residential settings. You might see it under deck posts, pergola posts, fence posts, or small porch columns. The square shape and these dimensions help spread the weight of these structures into the ground. It’s a typical choice when you need a footing that fits into tighter spaces but still offers enough size for light to moderate loads.

Whether this footing size works depends on several factors like how heavy the post or structure will be, the type of soil where it’s placed, and how deep the frost line is in your area. Reinforcement like rebar might be needed, and local building codes can affect what’s allowed. It’s important to consider these details before deciding on footing dimensions.

Common Mistakes to Avoid

Common mistakes to avoid when estimating and pouring this footing:

• Mixing up inches and feet when calculating volume.
• Forgetting to add a waste allowance; small jobs are especially sensitive to shortfalls.
• Ordering ready-mix without checking minimum delivery volume or extra costs.
• Neglecting to verify frost depth or local code requirements for depth and reinforcement.
• Failing to prepare and compact the subgrade or to use a small gravel pad if required.
• Not placing reinforcement or ties where the plan calls for them, which can reduce footing performance.