Blue-ocean drilled foundation workflow
Pier & Caisson Concrete Calculator
Answer first: calculate the straight shaft and optional bell separately, multiply by the pier count, add waste, then review excavation, casing, reinforcement, groundwater, access, inspection, and ready-mix scope before ordering.
4 straight 18 in x 8 ft piers
about 2.30 yd3 with 10% waste
That is about 104 common 80-lb bags or a 2.5 yd3 rounded ready-mix planning order.
18 in shaft + 36 in bell
shaft and bell calculated separately
Enter straight shaft height above the bell so the tapered base is not counted twice.
Shaft, bell, bags, and ready-mix order
Enter the straight shaft above the bell. The visual keeps the two volumes separate so a tapered base is not hidden inside one oversized cylinder.
Geometry map
Shaft height stops where the bell begins.
Per pier before waste
0.61 yd3
16.49 ft3 per approved detail.
Project with waste
2.69 yd3
2.05 m3 across 4 piers.
80-lb bag screen
121 bags
Uses 0.60 ft3 per bag; confirm the exact product yield.
Ready-mix screen
2.75 yd3
$470 material at the entered yd3 price before fees.
Interactive workflow
Run the numbers, then save or export the project
Save this estimate or download a PDF report
The PDF report uses the current calculated result. Save the estimate first when you want to reuse the inputs later.
What ordinary pier calculators miss
A clean volume answer is useful only when the dimensions mean the same thing on the drawing, in the hole, on the concrete ticket, and in the contractor quote.
| Benchmark says | Replace with local input | Next check |
|---|---|---|
| One cylinder for every pier | Separate the straight shaft from an approved belled base. Enter shaft height above the bell to avoid double-counting the tapered section. | Confirm shaft diameter, bell diameter, bell height, count, and tolerances from the approved detail. |
| Calculated volume equals ordered volume | Keep waste, overbreak, irregular excavation, casing displacement, pump priming, testing, and supplier order increments visible. | Ask who owns concrete overrun and how unused or returned concrete is billed. |
| Pier and caisson are interchangeable | Terminology varies by region and trade. The approved geometry, reinforcement, bearing detail, construction method, and inspection requirements control the work. | Use the project drawings and local professional language in the quote rather than relying on the label alone. |
Pier and caisson quote checklist
Use these checks before comparing a per-pier price or approving a concrete quantity.
| Signal to check | What it means | Next step |
|---|---|---|
| Approved geometry | The shaft diameter, straight height, bell dimensions, count, cut-off elevation, and concrete cover are stated. | Resolve missing dimensions with the designer or qualified local professional before ordering. |
| Excavation condition | Soil stability, casing or slurry, groundwater, rock, spoils, cave-in risk, overbreak, and cleanout responsibility are priced or excluded. | Ask how field overrun is measured and who approves a changed hole. |
| Reinforcement and embeds | Steel cage, dowels, anchor bolts, sleeves, templates, cover, chairs, lifting, and inspection timing are clear. | Keep steel and embed scope separate from concrete material volume. |
| Placement and testing | Truck or pump access, placement method, slump, testing, tremie needs, wait time, washout, and rejected-load responsibility are written. | Normalize delivery, pump, wait, and testing allowances across bids. |
| Structural boundary | The calculator has not been used to choose diameter, depth, bell size, bearing capacity, reinforcement, or load capacity. | Use approved drawings, geotechnical information, permits, and required inspections. |
Related concrete planning tools
Move from a single calculation into a purchase, proposal, or pour-day decision with connected calculators and checklists.
How do I calculate concrete for a round pier or caisson?
For a straight shaft, multiply pi by radius squared by the straight shaft height, then multiply by the number of piers. Add the separate bell volume when the approved detail includes a belled base, then add waste before ordering.
Are concrete belled piers the same as caissons?
The terms can overlap in everyday construction language, but usage varies by region, contractor, and design discipline. Do not use the label to infer structural equivalence. Use the approved shaft, bell, reinforcement, bearing, construction, and inspection details for the project.
How is a belled pier volume calculated?
This calculator treats the bell as a conical frustum between the shaft diameter and bell diameter. Enter only the straight shaft height above the bell, then enter the bell height separately so the bell is not counted twice.
Does the calculator design the pier diameter or depth?
No. It estimates concrete material from dimensions you already have. Bearing capacity, loads, settlement, frost, uplift, lateral resistance, reinforcement, bell geometry, casing, and code compliance require qualified local design and review.
Why can ordered concrete exceed calculated pier volume?
Drilled excavations can have overbreak, irregular sides, groundwater, cave-ins, casing effects, pump or tremie waste, testing, and supplier order increments. Confirm the field-measurement and overrun rules before placement.
Planning disclaimer
This pier and caisson calculator estimates material volume only. It does not design foundations or verify bearing capacity, loads, settlement, frost, uplift, reinforcement, casing, excavation safety, groundwater control, placement method, permits, inspections, or code compliance. Use approved drawings and qualified local professionals.