Concrete for strip footings, per 10 ft
| Width × depth | cu ft | yd³ | 80 lb bags |
|---|---|---|---|
| 12 × 6 in | 5.00 | 0.19 | 9 |
| 16 × 8 in | 8.89 | 0.33 | 15 |
| 20 × 10 in | 13.89 | 0.51 | 24 |
| 24 × 12 in | 20.00 | 0.74 | 34 |
Concrete for square footing pads
| Pad size | cu ft | 80 lb bags |
|---|---|---|
| 12 × 12 × 8 in | 0.67 | 2 |
| 16 × 16 × 8 in | 1.19 | 2 |
| 18 × 18 × 10 in | 1.88 | 4 |
| 24 × 24 × 12 in | 4.00 | 7 |
| 30 × 30 × 12 in | 6.25 | 11 |
How to calculate a footing
For a footing that wraps around a building, measure along the center of the footing on every side and add them up, so the corners aren't counted twice.
Footing size basics
Home footings are often 16 to 24 inches wide and 8 to 12 inches deep, with the bottom below the frost line. The right size depends on the load and your soil, so check your local building code or permit drawings before you dig.
Concrete for strip footings, per 3 m
| Width × depth | m³ | 25 kg bags |
|---|---|---|
| 30 × 15 cm | 0.135 | 12 |
| 40 × 20 cm | 0.240 | 21 |
| 50 × 25 cm | 0.375 | 33 |
| 60 × 30 cm | 0.540 | 47 |
Concrete for square footing pads
| Pad size | m³ | 25 kg bags |
|---|---|---|
| 30 × 30 × 20 cm | 0.018 | 2 |
| 40 × 40 × 20 cm | 0.032 | 3 |
| 45 × 45 × 25 cm | 0.051 | 5 |
| 60 × 60 × 30 cm | 0.108 | 10 |
| 75 × 75 × 30 cm | 0.169 | 15 |
How to calculate a footing
For a footing that wraps around a building, measure along the center of the footing on every side and add them up, so the corners aren't counted twice.
Footing size basics
Home footings are often 40 to 60 cm wide and 20 to 30 cm deep, with the bottom below the frost line. The right size depends on the load and your soil, so check your local building rules or plans before you dig.
Common questions
How much concrete do I need for a footing?
Multiply length by width by depth, all in feet, then divide by 27 for cubic yards. A 40 ft long footing that is 16 in wide and 8 in deep needs about 1.32 cubic yards.
How much concrete do I need for a footing?
Multiply length by width by depth, all in metres. A 12 m long footing that is 40 cm wide and 20 cm deep needs 0.96 cubic metres.
How deep should a concrete footing be?
Deep enough to sit below the frost line and on firm soil. In mild climates that can be 12 in; in cold climates it can be 4 ft or more. Your local building department sets the requirement.
How deep should a concrete footing be?
Deep enough to sit below the frost line and on firm soil. In mild climates that can be 30 cm; in cold climates it can be 1.2 m or more. Your local building rules set the requirement.
How many bags of concrete for a 24×24 footing?
A 24 × 24 in pad that is 12 in deep holds 4 cubic feet, so about 7 bags of 80 lb.
How many bags of concrete for a 60 × 60 cm footing?
A 60 × 60 cm pad that is 30 cm deep holds 0.108 m³, so about 10 bags of 25 kg.