Bored Pier Calculator
Calculate the concrete volume required for bored piers, based on diameter, depth and quantity.
Bored Pier Calculator
Estimate the concrete volume required for bored piers.
Estimating Concrete For Bored Piers
Bored piers are cylindrical concrete footings drilled and poured to reach stable bearing ground, commonly used beneath waffle and raft slabs on reactive soil, retaining walls, decks and verandahs. Because each pier is a cylinder, the concrete volume for one pier is π × radius² × depth, and this calculator multiplies that by however many piers your project needs.
A standard 450 mm diameter pier has a radius of 0.225 m, so a single pier 2 m deep uses roughly π × 0.225² × 2 ≈ 0.318 m³ of concrete. Multiply that by your pier count, add a 5 per cent order allowance, and you have a realistic volume to order from your supplier.
What Information You Need To Enter
Enter the number of piers, select a diameter from 300 mm to 900 mm, and enter the average depth in metres. Pier diameter and depth are typically specified in your engineering drawings or soil report based on the load each pier carries and the depth needed to reach suitable bearing ground.
Understanding Your Results
The calculator shows the concrete required, a recommended order volume with a 5 per cent allowance, the volume of soil that will be excavated (equal to the concrete volume, since each hole is backfilled with concrete), and the approximate concrete weight in tonnes.
Why Accurate Estimating Matters
Bored pier concrete is usually ordered as a single pump-fed pour, so knowing the volume in advance avoids running short mid-pour or paying for concrete you did not need. It also helps you budget pier work as part of a larger slab or retaining wall project.
Frequently Asked Questions
What diameter bored pier do I need?
This depends on the load the pier carries and your soil conditions, both confirmed by a structural engineer. 450 mm is a common diameter for residential footings, but larger piers are used for heavier loads.
How deep do bored piers need to go?
Pier depth depends on reaching suitable bearing ground, which varies significantly across Melbourne depending on soil type. A soil report and engineering drawings will specify the required depth for your site.
Are bored piers used with waffle and raft slabs?
Yes. Both our Waffle Slab Calculator and Raft Slab Calculator let you include bored pier costs as part of a full slab estimate.
Is the excavated soil volume the same as the concrete volume?
Yes, for a bored pier the hole is filled entirely with concrete, so the volume of soil removed is equal to the volume of concrete poured.
Do bored piers need a concrete pump?
Most residential bored piers are poured using a line pump due to limited access for a truck-mounted chute. This is factored into full slab estimates on our Waffle Slab and Raft Slab calculators.
Related Calculators & Services
Need An Exact Price, Not Just An Estimate?
The Bored Pier Calculator gives you a fast, useful planning figure. For a fixed, accurate price backed by a site assessment, request a free professional quotation from HPL Construction.
