Concrete, Brick & Masonry calculator
Post Hole Concrete Calculator
Estimate concrete volume for cylindrical post holes from hole diameter, depth, quantity and allowance.
Estimate concrete volume for cylindrical post holes from hole diameter, depth, quantity and allowance. Enter the project measurements first, then replace any default material or performance value with data for the product you intend to use. Check post displacement inside the hole carefully. The basic cylindrical estimate can overstate concrete if a large post occupies part of the hole. For tight orders, subtract post volume or keep the difference as allowance.
What you need to enter
The Post Hole Concrete Calculator uses the following project information to calculate the result.
- Diameter
- Height / depth
- Quantity
- Extra allowance (%)
Calculator result
Total cylindrical volume
How the Post Hole Concrete Calculator works
The Post Hole Concrete Calculator estimates total cylindrical volume from this relationship: π × radius² × height × count × allowance. Because the page is designed for concrete volume for cylindrical post holes, the calculation depends especially on post displacement inside the hole. Metric and imperial entries are normalised before the arithmetic so equivalent measurements produce equivalent results.
Post Hole Concrete Calculator worked example
Post Hole Concrete Calculator example: eight cylindrical holes 300 mm in diameter and 700 mm deep have a gross volume of about 0.40 m³. A large timber post occupies part of each hole, so decide whether to subtract that displacement or keep it as contingency. The important sense-check is post displacement inside the hole, because that can move the real requirement away from the neat theoretical result.
Important calculation assumptions
For concrete volume for cylindrical post holes, the basic cylindrical estimate can overstate concrete if a large post occupies part of the hole. For tight orders, subtract post volume or keep the difference as allowance.
Frequently asked questions
What dimensions or project figures does the Post Hole Concrete Calculator need?
Measure internal diameter and depth/height, then enter how many identical holes or columns are being calculated. Those entries form the basis for estimating concrete volume for cylindrical post holes.
Should I use a default value for post displacement inside the hole in the Post Hole Concrete Calculator?
Before relying on the Post Hole Concrete Calculator, check post displacement inside the hole. The basic cylindrical estimate can overstate concrete if a large post occupies part of the hole. For tight orders, subtract post volume or keep the difference as allowance.
How should I round the Post Hole Concrete Calculator result for purchasing?
For the Post Hole Concrete Calculator, treat the output as a decision aid rather than an isolated number. Use the volume as an ordering estimate and discuss practical load increments with the supplier. Excavation/formwork tolerances and placement losses usually justify a modest allowance.