Concrete Calculator: Isolated Footing Volume
Estimate concrete for isolated (pad) footings fast. Choose rectangular or circular and prismatic (constant plan) or sloped/stepped (frustum). Enter plan sizes, thickness, count, and a waste allowance. Optionally add a pedestal above the footing. Results show footing-only, pedestal, and total volumes in m³, yd³, and ft³ plus approximate bag counts. Notes, formulas, and FAQs included.
Results
Footing volume (per piece)
0.000 m³
0.000 yd³
0.00 ft³
Pedestal volume (per piece)
0.000 m³
0.000 yd³
0.00 ft³
Total with waste
0.000 m³
0.000 yd³
0.00 ft³
Approximate bag counts (total with waste)
US bag sizes (QUIKRETE® yield)
Yield per bag from QUIKRETE data sheet. Actual yield varies with placement and compaction. Source
Metric bag sizes
Edit yields to match your local supplier.
How to use this concrete calculator
- Select metric or US units.
- Pick the footing type (rectangular/circular, prismatic/frustum) and enter plan sizes with thickness.
- Set the quantity and waste allowance. Many projects add 4–10% for waste and over-excavation.
- Optional: add a pedestal above the footing (rectangular or circular) by size and height.
- Read per-piece and total volumes, then review bag counts for ordering. Round up.
Formulas and assumptions
- Rectangular prism:
V = L × W × T. - Rectangular frustum (sloped/stepped): Let
Ab = Lb×WbandAt = Lt×Wt. VolumeV = (T/3) × (Ab + At + √(AbAt)). - Circular prism:
V = π × (D/2)² × T. - Circular frustum (truncated cone):
V = (πT/12) × (Db² + DbDt + Dt²). - Pedestal rectangular:
V = B × D × H(B and D in mm/in converted to meters). - Pedestal circular:
V = π × (D/2)² × H. - Total:
Vpiece = Vfooting + Vpedestal, thenVtotal = Vpiece × n, andVwaste = Vtotal × (1 + waste%). - Notes: This estimates concrete only. Sizing of footing dimensions, reinforcement, cover, and soil bearing capacity must be by your engineer.
References
- Waste allowance ~4–10% typical in practice (NRMCA Concrete In Practice CIP 8, CIP 31).
- Frustum formulas: pyramidal frustum, conical frustum.
- US bag yields: QUIKRETE® Concrete Mix 1101 data sheet.
FAQs
What sizes should I use for an isolated footing?
Follow your structural engineer and geotechnical report. This tool only computes volume for the sizes you enter.
What’s the difference between prismatic and frustum footings?
Prismatic keeps the same plan size through the thickness. Frustum footings are wider at the base and narrower at the top (stepped or sloped sides). Use the frustum options to capture that shape accurately.
Should I include a pedestal?
Many columns sit on a short pedestal above the footing. If your drawings show one, add its size and height in the optional pedestal section.