How Much Concrete for a 12-Inch Round Footing 24 Inches Deep?
12" diameter × 24" deep round footing — 1.5708 cu ft (0.0582 yd³) and bag counts for ordering
Estimate concrete and bag counts for a 12-inch diameter, 24-inch deep round footing. Exact volume, a 10% waste plan, and 40/60/80-lb bag totals are provided for quick ordering.
If you're planning material for a narrow tube-form pour, this page is for a 12" diameter × 24" deep round footing. It's a small, confined pour: the cylinder holds 1.5708 cubic feet of concrete before any waste allowance.
This size is often handled with bagged concrete on site. Expect a shallow excavation of 24" and a tight circular form. I’ll show the exact volume first, then the planning totals with a 10% waste allowance so you can decide between bags and a ready-mix delivery.
Quick Answer
Exact volume: 1.5708 cubic feet (0.0582 cubic yards).
Planning with 10% waste: 1.7279 cubic feet (0.064 cubic yards). Exact bag counts are 6 40-lb bags, 4 60-lb bags, or 3 80-lb bags. With the 10% waste allowance plan to buy 6 40-lb bags, 4 60-lb bags, or 3 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 estimate and order concrete for this 12" × 24" round footing.
- Measure the inside diameter of the form and the poured depth; use 12" diameter and 24" depth for this page.
- Confirm the exact finished depth you will pour and use the cylinder formula for volume.
- Add a waste allowance (this page uses 10%) and round bag counts up to whole bags.
- Decide between bagged concrete for single pours or a small ready-mix truck for multiple holes.
- Multiply quantities by the number of footings before ordering and add one extra bag or a small contingency.
- Note the chosen bag size (40/60/80 lb) and order the corresponding number of bags.
Formula
Use this round footing formula:
Volume (ft³) = π × Radius (ft) × Radius (ft) × Depth (ft)
3.1416 × 0.5 × 0.5 × 2 = 1.57 ft³
1.57 ÷ 27 = 0.06 yd³
If you add a 10% waste allowance, you should plan closer to 0.06 cubic yards.
Worked Example
Single-footing example — before waste: 1.5708 cu ft (0.0582 yd³). With 10% waste: 1.7279 cu ft (0.064 yd³). Bag counts: exact use is 6 40-lb bags, 4 60-lb bags, or 3 80-lb bags; planning with 10% waste keeps those same buy quantities listed above.
Multiple-footing example (4 footings) — total: 6.2832 cubic feet, 0.2328 cubic yards. Total bag counts: 24 40-lb bags, 16 60-lb bags, or 12 80-lb bags (planning numbers with 10% waste shown as the same totals when rounded).
Bag Count Estimate
- 3 bags of 80 lb concrete mix
- 4 bags of 60 lb concrete mix
- 6 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 12" × 24" footing, bagged concrete is usually simpler. One person can mix a few 40-, 60-, or 80-lb bags and handle the small volume without a truck. You avoid minimum truck charges and long wait windows for a very small quantity.
If you're pouring several of these footings, ready-mix can become practical once the total volume nears a fraction of a yard and you prefer a single controlled pour. For just one or two holes, stick with bagged concrete; for many holes, compare the truck minimum and travel time to the labor involved in mixing multiple batches.
Common Uses for This Footing Size
This 12" diameter × 24" deep size is used for isolated post supports where the footprint is narrow: pergola posts, deck posts in tight layouts, small sign posts, or similar single-point supports that suit a cylindrical footing. The small volume and narrow tube form make it convenient where access is limited and a tight circular footprint is required.
Limits are governed by the load on the support, the soil bearing capacity at the site, frost depth in your area, and whether you need reinforcement in the pour. In some cases this size may work, but adequacy depends on those factors and any local building department requirements or permit considerations.
Common Mistakes to Avoid
Common estimating and ordering mistakes to avoid for this size footing:
- Skipping the waste allowance and ordering exactly 1.5708 cu ft worth of material.
- Using the outer tube diameter instead of the inside clear diameter when calculating volume.
- Mixing bag yields—assuming a 60-lb bag yields the same as an 80-lb bag.
- Ordering bag counts per footing and not multiplying by the total number of footings.
- Rounding down instead of up when converting fractional bag needs to whole bags.
- Not keeping a small spare supply on site for adjustments or spillage.
Frequently Asked Questions
What is the exact concrete volume for a 12" diameter by 24" deep round footing?
The exact volume is 1.5708 cubic feet, which is 0.0582 cubic yards.
How many bags of concrete do I need for this single footing?
Exact bag counts are 6 40-lb bags, 4 60-lb bags, or 3 80-lb bags for the single footing.
Why include a 10% waste allowance and how does it change the numbers?
A 10% waste allowance accounts for spillage, over-excavation, and mixing variance. The planning volume becomes 1.7279 cu ft (0.064 yd³) and the suggested buy quantities are the rounded bag totals shown on the page.
Will this footing size work for a deck or pergola post?
This size is sometimes used for deck or pergola posts in narrow layouts, but whether it is sufficient depends on the actual post load, soil bearing, frost depth, reinforcement, and any building department requirements.
Keep Planning Your Concrete Project
Use the calculator, compare more footing pages, and review your estimate before buying 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.