Free · Material quantities

Post-Hole Concrete Volume with Three-Times Hole Dimensions

Post-Hole Concrete Volume with Three-Times Hole Dimensions. Use retained unit selectors and documented geometric or area assumptions to calculate quantities and supported inverse relationships.

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Calculator inputs

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How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

Private by default

Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.

Formula and method

Example in initial displayed units: Post width 10, Post thickness 10, Post depth 1, Number of posts 3 gives Concrete volume for one post 0.08, Concrete volume for all the posts 0.24.

round: V = π((3d)²−d²)h/4; rectangular: V = ((3w)(3t)−wt)h; total = count×V

Worked example

Enter these known values and leave the other values blank.

Post width
10 cm
Post thickness
10 cm
Post depth
1 m
Number of posts
3
Concrete volume for one post
0.08 m³
Concrete volume for all the posts
0.24 m³

Assumptions and limitations

  • The retained model fixes each hole dimension at three times the corresponding post dimension: hole diameter 3d, or rectangular width 3w and thickness 3t. It subtracts the post volume over the entered buried depth. This is an explicit geometric assumption, not an excavation size or embedment design for every site. There is no independent hole-size control. Hole taper, irregular excavation, gravel, flared footings and waste allowances are excluded.
  • Use compatible units and enough independent measurements. Clear unknown quantities before solving backward; a rounded count does not uniquely determine original dimensions. Display rounding does not represent measurement uncertainty.
  • A count solved from total and per-item quantities must be a positive whole number. Rounded measurements can yield a fractional ratio; enter the actual known whole count rather than treating that ratio as a purchase or installation quantity.

Common questions

Can I specify a different hole diameter?

This retained workflow fixes hole size at three times each post dimension. Use a separate hole-minus-post volume calculation when the actual excavation differs.

References

The calculation equations, inverse formulas, units, and input rules were imported from this source. Bookify provides the interface and equation solver.

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