How Much Concrete for a 16-Inch Round Footing 24 Inches Deep?
Estimate for a 16" diameter × 24" deep round footing — 2.7925 cu ft, 0.1034 yd³, bag counts shown
Exact volume, cubic yards, and bag counts for a 16" diameter × 24" deep round footing. Includes exact material needed and a 10% waste-adjusted planning total for bagged concrete.
A narrow tube-form pour for a single post under a deck or pergola: 16" diameter × 24" deep. This is a small-volume round footing poured in a Sonotube-style form.
Expect a shallow excavation of 24" and a quick mix or a handful of bags to finish the pour. Use the numbers below to decide between bags of concrete mix or a small ready-mix delivery and to size reinforcement if required by your design.
Quick Answer
Exact volume: 2.7925 cubic feet (0.1034 cubic yards) for a single 16" diameter × 24" deep round footing.
Planning with 10% waste: 3.0718 cubic feet (0.1137 cubic yards). Bagged estimates: 11 40-lb bags, 7 60-lb bags, or 6 80-lb bags (these are waste-adjusted planning counts).
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 exact footing size:
- Measure the form outside diameter and depth to confirm 16" × 24".
- Use the cylinder volume (volume already calculated here) to verify your quantities.
- Add a 10% waste allowance to get the planning totals shown.
- Decide material: bags for one or two footings, ready-mix for several identical footings.
- If pouring multiple footings, multiply the planning volumes and bag counts before ordering.
- Round up bag counts to whole bags and confirm delivery timing for ready-mix if you choose that route.
Formula
Use this round footing formula:
Volume (ft³) = π × Radius (ft) × Radius (ft) × Depth (ft)
3.1416 × 0.67 × 0.67 × 2 = 2.79 ft³
2.79 ÷ 27 = 0.1 yd³
If you add a 10% waste allowance, you should plan closer to 0.11 cubic yards.
Worked Example
Single footing: Exact volume before waste: 2.7925 cu ft (0.1034 cu yd). With 10% waste: 3.0718 cu ft (0.1137 cu yd). Planning bag counts: 11 40-lb bags (planning), exact 10 40-lb bags.
Multiple footings (4 posts): Total exact volume = 11.17 cu ft (0.4136 cu yd). Total with 10% waste = 12.2872 cu ft (0.4548 cu yd). Bagged planning total = 44 40-lb bags (11 × 4 planning bags).
Bag Count Estimate
- 6 bags of 80 lb concrete mix
- 7 bags of 60 lb concrete mix
- 11 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
Bagged concrete is often simpler for this single 16" × 24" footing. One pour fits in a wheelbarrow or mixing tub and uses about 11 40-lb bags with waste, so you avoid minimum delivery charges.
If you have several identical footings, ready-mix becomes more attractive. When totals approach a few tenths of a cubic yard per footing repeated several times (for example, 6–10 footings), a small truck delivery can save time and reduce per-footing waste.
Common Uses for This Footing Size
This 16" diameter × 24" deep footing is often used for isolated post supports such as pergola posts, single deck posts, small porch column bases, or sign supports where a narrow cylindrical layout is preferred. The small footprint works when supporting a single vertical load in limited space.
Limits include the load magnitude, soil bearing capacity, frost depth, and whether reinforcement is needed. Actual adequacy depends on those site-specific factors and any permit or design requirements for your project.
Common Mistakes to Avoid
Common estimating and planning oversights to avoid:
- Ordering only the exact volume and not adding the 10% waste allowance.
- Confusing exact bag counts with the waste-adjusted planning counts.
- Using outside form diameter without checking wall thickness of the tube form.
- Forgetting to multiply bag counts correctly when ordering multiple footings.
- Assuming one type of bag (40-lb vs 60-lb vs 80-lb) without recalculating counts for that bag size.
- Waiting to mix until you have the exact number of bags on site — always round up to whole bags.
Frequently Asked Questions
What is the exact concrete volume for a 16" diameter × 24" deep round footing?
The exact volume is 2.7925 cubic feet, which is 0.1034 cubic yards.
How many bags of concrete do I need for this footing?
Exact bag counts (no waste): 10 40-lb bags, 7 60-lb bags, or 5 80-lb bags. Planning counts with 10% waste: 11 40-lb bags, 7 60-lb bags, or 6 80-lb bags.
Why is a 10% waste allowance used and how does it change ordering?
The 10% allowance covers spillage, small over-excavation, and finish loss. It raises the volume from 2.7925 cu ft to 3.0718 cu ft and increases the 40-lb bag count from 10 to 11 for ordering.
Will this footing size be adequate for a deck or pergola post?
A 16" × 24" footing may work in some cases for deck or pergola posts, but adequacy depends on load, soil bearing, frost depth, reinforcement, and any permit or engineering requirements for the project.
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.