How Much Concrete for a 12x24x24 Footing?
12" x 24" x 24" footing: cubic feet, cubic yards, and recommended bag counts with 10% planning waste.
A 12" x 24" x 24" footing holds 4.0 cubic feet (0.1481 yd³). This page gives exact volume, waste-adjusted planning quantities, and bag counts for ordering or on-site mixing.
12" x 24" x 24" describes a rectangular footing 1 foot long, 2 feet wide, and 2 feet deep. That footprint works well for a single post base or a small column support where a deeper embedment is required.
This size often appears in residential projects for deck posts, light columns, or shed corner pads. Check local frost-depth rules and permit requirements: this footing may be suitable where a 24-inch depth aligns with local frost-depth requirements, but reinforcement, soil-bearing capacity, and any required inspections should be confirmed before pouring.
Quick Answer
Exact concrete volume for a 12" x 24" x 24" footing is 4.0 cubic feet, which equals 0.1481 cubic yards. Exact bag counts for the raw volume are 14 40-lb bags, 9 60-lb bags, or 7 80-lb bags.
Plan for waste and handling by adding 10%: planning volume is 4.4 cubic feet (0.1629 yd³). For ordering, use the waste-adjusted counts: about 15 40-lb bags, 10 60-lb bags, or 8 80-lb bags.
Need a custom estimate? Use the Footing Calculator. Browse footing size pages. All project pages.
How to Use This Footing Estimate
Quick steps to order and pour a 12" x 24" x 24" footing:
- Measure the footing footprint and depth to confirm the 12" × 24" × 24" dimensions on-site.
- Calculate volume and add a 10% waste allowance before buying materials.
- Decide between bagged concrete or ready-mix based on access, batch size, and supplier minimums.
- If using bags, buy the planning number of bags and mix on-site following manufacturer instructions.
- Set formwork, place any required reinforcement (rebar or wire), pour, consolidate, and level the concrete.
- Cure the pour per standard practice and protect from freezing or rapid drying during the first days.
Formula
The rectangular footing volume formula is length × width × depth, using feet to get cubic feet. For this footing: 1 ft × 2 ft × 2 ft = 4.0 cubic feet.
Convert cubic feet to cubic yards by dividing by 27. So 4.0 cu ft ÷ 27 = 0.148148... yd³, shown here as 0.1481 yd³.
To allow for cutting, spillage, and slight over-excavation, add the default 10% waste: 4.0 cu ft × 1.10 = 4.4 cu ft. Convert that to cubic yards: 4.4 ÷ 27 = 0.162962... yd³, rounded here to 0.1629 yd³.
Worked Example
Single footing example: one 12" x 24" x 24" footing requires 4.0 cubic feet (0.1481 yd³) of concrete. With 10% waste, order 4.4 cubic feet (0.1629 yd³), or about 15 40-lb bags, 10 60-lb bags, or 8 80-lb bags to be safe.
Multiple-footing example: three identical footings total 12.0 cubic feet (3 × 4.0 cu ft) of concrete, which is 12.0 ÷ 27 = 0.4444 yd³. With 10% waste plan for 13.2 cubic feet, or 13.2 ÷ 27 = 0.4889 yd³. For bags that means roughly 45 40-lb bags, 30 60-lb bags, or 24 80-lb bags total for the three footings.
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
Because a single 12" × 24" × 24" footing is only 0.1481 cubic yards (0.1629 yd³ with waste), bagged concrete is often the most practical option for one or two footings. Bags let you mix exactly what you need on-site and avoid minimum-order constraints from some ready-mix suppliers.
Ready-mix offers better consistency and less on-site labor for larger jobs, but many suppliers have a minimum delivery (commonly around a half-yard). For a single footing this is usually more than you need, so bags of concrete mix are typically the cost-effective choice unless you have several footings or another adjacent pour to combine.
If access, manpower, or finish consistency are concerns, compare the labor and time costs for mixing bags versus the convenience of a ready-mix delivery and choose the method that minimizes waste and meets site constraints.
Common Uses for This Footing Size
A 12x24x24 footing is often used for supporting deck posts, pergola posts, fence posts, or small porch columns. Its rectangular shape and size can handle single-point loads where the weight isn’t too heavy. This footing can work for projects where a post needs a solid base to sit on, especially in residential settings with lighter structures. It’s common when the post isn’t carrying a large beam or heavy roof load.
Whether this footing size is suitable depends on several factors like the weight it needs to support, the type of soil, how deep the frost line is in your area, and if any reinforcement is necessary. Local building codes also play a role in determining if this footing meets the requirements for your specific project and location.
Common Mistakes to Avoid
Common mistakes to avoid when ordering and placing concrete for this footing size:
- Underestimating material by skipping the waste allowance and coming up short on-site.
- Confusing exact bag counts with the waste-adjusted planning counts and ordering the wrong quantity.
- Not checking local frost-depth and permit requirements before finalizing depth and reinforcement.
- Failing to set or secure formwork properly so dimensions shift during the pour.
- Skipping reinforcement or using undersized rebar when required by code or engineer recommendations.
- Mixing bags inconsistently or pouring in temperatures that prevent proper curing.
Frequently Asked Questions
How much concrete does a 12" x 24" x 24" footing need in cubic feet and cubic yards?
A single 12" x 24" x 24" footing requires 4.0 cubic feet of concrete, which equals 0.1481 cubic yards.
How many bags of concrete do I need for this footing?
Exact bag counts for the raw 4.0 cu ft volume are 14 40-lb bags, 9 60-lb bags, or 7 80-lb bags. For ordering include 10% waste: plan on about 15 40-lb bags, 10 60-lb bags, or 8 80-lb bags.
Why should I add 10% waste when ordering concrete for a footing?
Adding 10% covers minor over-excavation, spillage, uneven subgrade, and cutting losses so you don’t run short during the pour. The planning volume here increases from 4.0 cu ft to 4.4 cu ft (0.1629 yd³) with a 10% allowance.
Is a 12" x 24" x 24" footing adequate for a deck post?
It depends on the deck load, soil-bearing capacity, local frost-depth requirements, and code or engineer specifications. A 24-inch depth may meet frost requirements in some areas, but check local building department rules, verify soil conditions, and be prepared to add reinforcement or increase size if required.
Keep Planning Your Concrete Project
Use the calculator, compare footing pages, and keep your estimate practical before you buy materials.
Disclaimer: This page provides planning estimates only. Actual concrete needs vary with excavation accuracy, site conditions, local code requirements, bag yield, and supplier guidance. Always verify measurements before buying materials, and consult a qualified professional for structural or code-sensitive work.