# Strip Footing Calculator

Concrete, blinding, formwork and base area for strip footings.

- Page: https://jianzhujisuan.com/en/strip-footing
- Category: Concrete (https://jianzhujisuan.com/en/c/concrete)
- Chinese version: https://jianzhujisuan.com/zh/strip-footing.md
- Data checked: 2026-10-25

## Quick result

With the default inputs (Total length 60 m, Section shape Rectangular, Top width 0.37 m, Bottom width 0.6 m, Footing height 0.3 m, Blinding thickness 0.1 m, Blinding projection 0.1 m, Concrete waste 2%): **Footing concrete 11.02 m³**

## Inputs

| Parameter | Type | Default | Unit | Note |
|---|---|---|---|---|
| Total length | number | 60 | m | Sum of all strip lengths |
| Section shape | select | Rectangular | — |  |
| Top width | number | 0.37 | m |  |
| Bottom width | number | 0.6 | m | For rectangular sections the bottom width is used and top width ignored |
| Footing height | number | 0.3 | m |  |
| Blinding thickness | number | 0.1 | m | Set 0 for no blinding |
| Blinding projection | number | 0.1 | m | Usually 100 mm each side |
| Concrete waste | number | 2 | % |  |

## Formula

- **Section (rectangular)**: A = bottom width × height
- **Section (trapezoidal)**: A = (top + bottom) ÷ 2 × height
- **Concrete volume**: V = A × total length × (1 + waste)
- **Blinding**: V = (bottom + 2 × projection) × thickness × length
- **Side formwork**: S = 2 × side length × total length
- **Sloping length**: L = √(height² + ((bottom − top) ÷ 2)²)

## Worked example

60 m of 0.6 m by 0.3 m footing with 100 mm blinding projecting 100 mm: 11.02 m³ of concrete (10.80 net), 4.80 m³ of blinding, 36.0 m² of side formwork, 12.0 m² of blinding formwork and 36 m² of base area.

## Questions

### Why not multiply height by length for a trapezoidal footing?

Because the sides are battered and the formwork lies on the slope, whose length is √(h² + ((bottom − top)/2)²) — longer than the vertical height. For 370 top, 600 bottom and 300 high the sloping length is 321 mm, 7.1% more. Small on one section, but 60 m of wall adds 2.55 m², and flatter slopes differ far more. Missing this overruns the formwork budget.

### Does blinding need formwork?

Depends on method. Blinding cast directly against undisturbed soil (earth mould) needs no formwork — only concrete is measured. Cast on fill or against brick templates, it needs side formwork. Most footing blinding uses the earth mould, so budgets usually omit it, though a site instruction can claim it if formwork was actually erected. It is listed separately here so you can take it or leave it.

### How is the stepped brick footing calculated?

The stepped courses are measured by volume, usually by the equivalent-height method: the step volume is converted to an equivalent height of the same wall width and added from a table. Equal courses (quarter-brick offset every two courses) and alternate courses differ. Brick footing volume = wall width × (design height + equivalent height) × length, less ring beams, tie columns and ground beams.

## Related tools

- [Concrete Volume Calculator](https://jianzhujisuan.com/en/concrete-volume): Enter length, width and thickness to get the concrete volume you need and how many truck loads that is.
- [Formwork Area Calculator](https://jianzhujisuan.com/en/formwork-area): Pick a member type, enter section and length, and get the formwork contact area plus sheet and batten estimates.
- [Concrete Mix Design Calculator](https://jianzhujisuan.com/en/concrete-mix-ratio): Work out cement, sand, gravel and water per cubic metre from the target grade and water-cement ratio.
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- [Concrete Pour Sequencing Calculator](https://jianzhujisuan.com/en/concrete-pour-plan): Divide a slab into strips and get the volume, truck count and duration for each pour.
- [Concrete Strength Converter](https://jianzhujisuan.com/en/concrete-strength-convert): Convert between grade, MPa, psi and kgf/cm², with cube-to-cylinder correction.

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Generated by BuildCalc. All calculations run in your browser; no data is uploaded. Formulas follow national standards and common trade practice; local codes govern.