Concrete Column & Pier Calculator

Get concrete volume and rebar for round or square columns, piers, and post footings — plus tools, cost, and a pour plan.

1. Draw your slab
Drag on the grid to draw. Snap shapes together, weld them into one slab, and hover a shape to add a connected piece with the +.

Add shape

Layers

Add a shape or drag on the grid to start your slab.

0'5'10'15'20'25'0'5'10'15'
2 ft
Drag to draw · grid = 1' control joints

Selected shape

Select a shape to edit its size, snap it to others, or weld it into one slab.

Arrows nudge · ⌫ delete · ⌘C / ⌘V copy & paste

2. Answer a few questions
Tell us what the slab is for and we'll suggest a thickness, base, strength, and reinforcement — override anything.

Structural. Poured to undisturbed soil, no gravel base.

Suggested 8"
Sold by the cubic yard; short-load fees apply under ~5 yd.

Vapor barrier

6-mil poly under interior / enclosed slabs

Include tool rental in total

Add advisory rental/buy estimates to the grand total

Extra concrete for spillage and uneven subgrade. 10% is typical.

3. Your plan
Materials, tools, cost, and a step-by-step build plan. Every unit price is editable.

Concrete

0.26 yd³

Footprint

0 ft²

Perimeter

0 ft

Concrete$83

Ready-mix concrete (3000 psi)

0.5 cu yd · Under 1 yd — most plants have a minimum + short-load fee. Bagged may be cheaper.

Alt: Bagged: 12 x 80 lb bags

$83

Materials$83
Tool rentalnot in total$115
Estimated total$83

From US average prices — click any price to match a local quote. Excludes delivery, permits, and labor.

Tools you'll need

  • WheelbarrowMove and place the concrete.
  • Screed board (straight 2x4)Longer than the form is wide.
  • Bull floatrent ~$55/dayFlatten and close the surface after screeding.
  • Magnesium hand floatDetail work and edges.
  • EdgerRounds and strengthens the slab perimeter.
  • GrooverTools control joints into the wet slab.
  • Shovel, steel rake & margin trowelSpread, pull, and detail the pour.
  • Gloves, eye protection & rubber bootsWet concrete is caustic — cover up.
  • Concrete saw + diamond bladerent ~$60/dayOnly if you cut control joints the next day instead of tooling them wet.

Rental prices show only for specialty gear — skip them if you already own it.

Step-by-step plan

Your build, tracked

Save this plan to Blueprint

Turn your slab into a project with the full step-by-step plan, tool list, and shopping list you can check off as you build — about $83 in materials.

About the concrete column & pier calculator

Overview

Columns, piers, and Sonotube pours are priced by volume: the cross-section area times the height, times the count. Round columns use π r² and square columns use side², so a handful of 12-inch piers can add up faster than people expect. Enter the profile, size, height, and how many, and this tool returns the exact concrete, the rebar cage, the tools, and a pour plan.

You can mix column types and add a footing or slab so the whole pour is estimated together. Every unit price is editable, and the plan covers plumbing the forms and suspending the rebar.

How to use this tool
  1. Choose round or square, then enter the diameter or side in inches.
  2. Set the height in feet and the number of identical columns or piers.
  3. Add more columns of different sizes, or a footing/slab, if your pour includes them.
  4. Review the concrete volume and rebar, editing any unit price to a local quote.
  5. Follow the plan to form, reinforce, and pour, then save it to Blueprint.
Frequently asked questions

How much concrete does a 12-inch column need?

A round 12-inch (1 ft) diameter column is π × 0.5² = about 0.79 cubic feet per foot of height, so an 8-foot column is roughly 6.3 cubic feet (about 0.23 cubic yards). This tool multiplies by your count and adds a waste allowance.

How much concrete fits in a Sonotube?

Sonotubes are sized by inside diameter, the same as a round column here. Enter the tube's diameter and the pour height. An 8-inch tube holds about 0.35 cubic feet per foot; a 12-inch tube about 0.79.

Do concrete piers need rebar?

Structural piers and columns are typically reinforced with a vertical rebar cage (often #4 bars with ties) doweled into the footing. Deck piers and post footings may use a single bar or none for light loads — check your local code.

How deep should a pier or post footing be?

Footings must reach below the local frost line (often 12 to 48 inches depending on climate) and bear on undisturbed soil. Set the height to your total pour depth including any bell or pad at the base.

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Plan the whole project

Turn these numbers into a full project plan

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