How to Calculate Footing Concrete Volume
Accurate volume estimation for concrete footings is essential to establish a strong structural foundation without costly over-ordering. This calculator provides precise volume requirements for both continuous strip footings (rectangular) and isolated pier bases (circular).
Key Features of Our Free Footing Concrete Calculator
Rectangular / Square Footings
Compute volume with L × W × D for isolated or strip footings—unit conversions handled internally.
Circular Footings
Use diameter and depth to calculate π × r² × D for round pads and pier bases.
Multi-Unit Inputs
Enter dimensions in meters, centimeters, feet, or inches; we convert to a common base for accuracy.
Waste Allowance Built-In
Add any waste percentage (commonly 5–10%) to cover over-excavation and placement losses.
Display Units Toggle
Show results in m³, yd³, or ft³ without re-entering values.
Gated Results
Results appear after you click Calculate—keeps the form focused and prevents accidental reads.
Print / Save + Yardage Helper
Export a tidy summary and view yd³ with +5% and +10% helpers for supplier rounding.
How to Use the Footing Concrete Calculator
- 1Select the Rectangular / Square or Circular tab.
- 2Choose your input unit (m, cm, ft, or in) and enter dimensions.
- 3Add a Waste Allowance (%)—5–10% is typical for footings.
- 4Click Calculate to reveal Net Volume, With Waste, and Waste Added.
- 5Set Show in to view m³, yd³, or ft³, and use the yd³ helper (+5% / +10%) for ordering.
- 6Use Print / Save Calculations to export a clean summary.
Why Choose Our Footing Concrete Calculator?
- Supports both rectangular/square and circular footings in one place.
- Accurate unit handling across m, cm, ft, and in—no manual conversions needed.
- Waste % included to reduce the risk of under-ordering due to over-excavation.
- Switch display units instantly for engineering checks or ready-mix ordering.
- Printable results streamline site approvals and purchase orders.
Types of Concrete Footings
Knowing which footing you are pouring helps you pick the right geometry tab and a realistic depth. The most common residential and light-commercial footing types are:
Strip / Continuous Footing
A long, rectangular run beneath load-bearing walls. Use the Rectangular tab and enter the full wall length as L. Sized by wall load and soil bearing capacity.
Isolated / Spread (Pad) Footing
A square or rectangular pad under a single column or post. Enter L × W × D on the Rectangular tab; multiply by quantity for repeated pads.
Circular / Pier Footing
Round bases for deck posts, sonotubes, and pier-and-beam systems. Use the Circular tab with diameter and depth (π × r² × D).
Combined Footing
Supports two or more columns on one slab where individual pads would overlap or sit too close to a property line. Model the overall footprint as a rectangle.
Stepped Footing
Steps down sloping ground or between differing foundation depths. Calculate each step as a separate rectangular segment and add the volumes.
Pile Cap
A thick block that transfers a column load onto a group of piles. Estimate the cap as a rectangular prism; reinforcement follows the engineer's design.
Formulas Used in the Calculator
- 1) Rectangular / Square FootingVolume = Length × Width × Depth (Thickness)
Inputs are converted to meters internally before multiplication to keep units consistent. - 2) Circular FootingVolume = π × r² × Depth, where r = Diameter ÷ 2
- 3) Waste AllowanceAdjusted Volume = Raw Volume × (1 + Waste%)
Typical waste for footings is 5–10% depending on excavation, formwork, and placement method. - 4) Display Conversions1 m³ = 35.3147 ft³
1 m³ = 1.30795 yd³
yd³ = ft³ ÷ 27
Concrete Volume for Common Footing Sizes
For continuous strip footings, concrete scales with length. The table below shows the volume per linear foot for common width × depth combinations, plus the total for a 10-foot run, so you can sanity-check the calculator at a glance.
| Footing (Width × Depth) | Per Linear Foot (ft³) | Per 10 ft Run (yd³) |
|---|---|---|
| 12" × 6" | 0.50 | 0.19 |
| 16" × 8" | 0.89 | 0.33 |
| 18" × 8" | 1.00 | 0.37 |
| 20" × 10" | 1.39 | 0.51 |
| 24" × 12" | 2.00 | 0.74 |
Isolated pad footings are simpler: enter Length × Width × Depth directly on the Rectangular tab. For round deck or pier footings, switch to the Circular tab — a 12" diameter × 36" deep pier needs about 2.36 ft³ (≈ four 80 lb bags).
Standards & References
The primary U.S. structural concrete code, covering design and construction requirements for footings, foundations, columns, beams, and all reinforced concrete elements.
Guides selection of water-cement ratio, aggregate sizes, and mix proportions to achieve specified concrete strength for footing applications.
Covers requirements for ready-mixed concrete supplied by truck — the standard delivery method for footing pours on most construction projects.
Footing depth must extend below the local frost line per IRC R403.1.4 and soil bearing capacity must be confirmed by a licensed geotechnical or structural engineer before sizing footing dimensions and concrete volume.
When to Use This vs. Related Calculators
Use the Footing Concrete Calculator for shallow spread footings — continuous strip, isolated pad, and combined footings that bear near grade. For deck posts poured in cardboard tube forms, the Sonotube concrete calculator is purpose-built for that cylindrical geometry. Larger drilled shafts and belled caissons belong in the pier and caisson concrete calculator. When a monolithic pour includes both a slab and a thickened perimeter footing in one operation, the monolithic slab calculator handles both components together. For the slab that sits on top of the footing, the slab concrete calculator covers that pour. Rebar quantities for the footing are handled by the rebar calculator.
Frequently Asked Questions
Can I calculate both rectangular and circular footings?
Yes. Use the tabs to switch between Rectangular/Square and Circular modes; each uses the appropriate geometric formula.
Which input units are supported?
Meters (m), centimeters (cm), feet (ft), and inches (in). You can display results in m³, yd³, or ft³.
How much waste should I add for footings?
5–10% is common to account for over-excavation, trench irregularities, and placement losses. Follow your project specifications.
What does the yards helper do?
It provides yd³ with +5% and +10% additions to quickly round orders for ready-mix deliveries.
Does this include rebar, cover, or mix design?
No. The calculator focuses on volume. Reinforcement and mix grade must follow your structural drawings and local codes.
How deep should a concrete footing be?
Footings must bear on undisturbed soil and extend below the local frost line — often 12 to 48 inches depending on your climate zone. Residential strip footings are commonly 8–12 inches thick and at least as wide as the wall plus the bearing required by your soil. Always confirm depth against your local building code (IRC/IBC).
How many bags of concrete do I need for a footing?
Divide the total volume by the bag yield: an 80 lb bag makes about 0.6 ft³, a 60 lb bag about 0.45 ft³, and a 40 lb bag about 0.30 ft³. For example, a 2.36 ft³ pier needs roughly four 80 lb bags. Beyond about 1 cubic yard (≈ 45 × 80 lb bags), ordering ready-mix is usually cheaper and faster.
How much concrete is needed for a deck footing?
Round deck footings are calculated with the Circular tab. A 12-inch diameter footing poured 36 inches deep takes about 2.36 ft³ (≈ 0.09 yd³, or four 80 lb bags). If you are using cardboard tube forms, our Sonotube concrete calculator is purpose-built for that job.
Related Calculators
Slab Concrete Calculator
Estimate concrete for slabs, patios, and floors.
Monolithic Slab Concrete Calculator (Slab + Thickened-Edge Footing)
Calculate concrete volume for a monolithic slab — slab body plus integral perimeter footing in a single pour. Garage, house foundation, and shed presets with ACI 318 and IRC R403 compliance checks.
Wall Concrete Calculator
Vertical concrete wall volumes, single or multi-segment.
Pier / Caisson Concrete Calculator
Cylindrical shafts and drilled piers by length.
Rebar Calculator
Estimate rebar bars, linear footage, weight, and cost for slabs, footings, and walls.
Beam Concrete Calculator
Estimate concrete for beams and lintels.