How Much Concrete for a 30-Inch Round Footing 24 Inches Deep?
30" round footing, 24" deep — 9.82 cu ft (0.3636 yd³) and bag counts for ordering
Estimate concrete for a 30-inch diameter Sonotube footing 24 inches deep: exact volume, cubic yards, and bag counts both exact and with a 10% waste allowance.
Planning the pour for a 30" diameter × 24" deep round footing starts with the volume: this is a narrow tube-form footing with under 10 cubic feet of concrete. The tube form and 24" depth mean a small, controlled pour you can often handle with bags.
Use this page to see the exact volume for one footing and the waste-adjusted totals used for ordering. Note excavation depth and reinforcement needs may change what you actually buy.
Quick Answer
Exact volume: 9.8175 cubic feet (0.3636 cubic yards) for one 30" diameter × 24" deep round footing.
Planning with 10% waste: 10.7993 cubic feet (0.4 cubic yards). Exact bag counts: 33 40-lb bags, 22 60-lb bags, 17 80-lb bags. Planning bag counts (with waste): 36 40-lb bags, 24 60-lb bags, 18 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 prepare purchase quantities for this footing size.
- Measure the footing diameter and depth on site and confirm 30" × 24" is correct.
- Check the exact volume (9.8175 cu ft) and the waste-adjusted volume (10.7993 cu ft).
- Decide bag size: calculate exact bags first, then use the planning bag counts with 10% waste.
- If ordering multiple footings, multiply the planning volumes and bag counts before ordering.
- Pick bagged concrete for a single footing; evaluate ready-mix once total yards rise above about 1.5–2 yd³.
- Round up bag counts to whole bags and confirm delivery timing with suppliers.
Formula
Use this round footing formula:
Volume (ft³) = π × Radius (ft) × Radius (ft) × Depth (ft)
3.1416 × 1.25 × 1.25 × 2 = 9.82 ft³
9.82 ÷ 27 = 0.36 yd³
If you add a 10% waste allowance, you should plan closer to 0.4 cubic yards.
Worked Example
Single footing: before waste the footing needs 9.8175 cu ft (0.3636 yd³). With a 10% allowance plan on 10.7993 cu ft (0.4 yd³) and the planning bag counts listed above.
Multiple footings: for four identical footings the total before waste is 39.27 cu ft (1.4544 yd³). With 10% waste plan on 43.1972 cu ft (1.6 yd³) — that equates to 144 40-lb bags, 96 60-lb bags, or 72 80-lb bags for the four-footing set (planning counts).
Bag Count Estimate
- 18 bags of 80 lb concrete mix
- 24 bags of 60 lb concrete mix
- 36 bags of 40 lb concrete mix
Always verify the actual yield on the product label before buying materials.
Bag Counts by Waste Buffer for 30" diameter × 24" deep
Pick a buffer based on site conditions: clean forms and accurate measurements can run leaner; rough subgrade or hard-to-reach pours need more cushion.
| Buffer | Volume (ft³) | 80 lb bags | 60 lb bags | 40 lb bags |
|---|---|---|---|---|
| No buffer | 9.82 | 17 | 22 | 33 |
| +5% typical DIY | 10.31 | 18 | 23 | 35 |
| +10% recommended | 10.8 | 18 | 24 | 36 |
| +15% rough conditions | 11.29 | 19 | 26 | 38 |
When Bagged Concrete vs Ready-Mix Makes Sense
For a single 30" × 24" footing, bagged concrete is usually simpler: you can mix what you need on site and avoid minimum truck loads. The small volume (about 0.4 yd³ with waste) fits well into bags and reduces leftover ready-mix waste.
If you have several footings and the combined planned volume approaches or exceeds roughly 1.5–2.0 cubic yards, ready-mix starts to make sense. At that point a small truck can save time and ensure uniform mix quality across multiple pours.
Common Uses for This Footing Size
This 30" diameter × 24" deep round footing often suits isolated post supports where a narrow cylindrical layout fits the design: pergola posts, deck or porch posts, smaller sign supports, or single-column bases where the compact footprint is a priority.
Limits matter: the footing’s real adequacy depends on load, soil bearing, frost depth, reinforcement, and permit requirements. Confirm those conditions and reinforcement needs before relying on this size for heavier or higher loads.
Common Mistakes to Avoid
Common estimating and ordering mistakes to avoid for this footing size:
- Using the diameter instead of the radius when calculating volume.
- Forgetting a waste allowance and under-ordering bags.
- Mixing bag counts and ready-mix quantities without converting units consistently.
- Ordering exact bag counts and not rounding up to whole bags.
- Not multiplying planning totals correctly when ordering multiple footings.
- Assuming reinforcement or a thicker footing won’t change the volume needed.
Frequently Asked Questions
How much concrete is in one 30-inch round footing 24 inches deep?
One footing holds 9.8175 cubic feet of concrete, which is 0.3636 cubic yards.
How many bags of concrete does one footing require?
Exact bag counts are 33 40-lb bags, 22 60-lb bags, or 17 80-lb bags. With a 10% waste allowance plan on 36 40-lb, 24 60-lb, or 18 80-lb bags.
Why include a 10% waste allowance and how is it applied?
A 10% allowance covers small measurement errors, spillage, and minor over-depths. Multiply the exact volume by 1.10 to get the planning volume used to calculate bag counts.
Is this footing size adequate for a deck post or pergola column?
This size may work in some cases for a deck post or pergola column, but adequacy depends on the applied load, soil bearing capacity, frost depth, and reinforcement. Confirm those factors before finalizing the footing size.
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.