Concrete Column Calculator — Concrete-Depot.com

Calculate concrete volume, rebar requirements, formwork, and cost for round, square, rectangular, hexagonal, or octagonal columns with live 3D visualization.

Column Shape

Diameter (IN) Inside diameter of form tube

Height (FT) Total column height

Quantity Number of columns

Waste (%) Recommended 10%

Unit System

Rebar Cage (Optional)

Include rebar calculation

Cost Estimation (Optional)

Calculate cost

Advanced Options

Concrete Strength (PSI)

Project Name (for PDF)

Volume

Total Concrete Volume –

In Cubic Feet –

In Cubic Meters –

With Waste –

Weight & Bags

Estimated Weight –

40 lb Bags –

60 lb Bags –

80 lb Bags –

Rebar Cage

Total Rebar Length –

Total Rebar Weight –

Rebar Cost (est.) –

Formwork & Materials

Formwork Surface Area –

Water Required –

Cement (for DIY mix) –

Sand (for DIY mix) –

Gravel (for DIY mix) –

Sonotube Recommendation

Recommended Size –

Time Estimates

Pour Time (est.) –

Curing Time (to 70%) –

Cost Estimate

Ready-Mix Cost –

Bagged Concrete Cost –

Total Estimated Cost –

📖 How to Use This Calculator

Select column shape: Choose from round, square, rectangular, hexagonal, or octagonal.
Enter dimensions: Input diameter or width/depth in inches or centimeters.
Set height: Enter the total column height in feet or meters.
Specify quantity: Enter the number of identical columns.
Adjust waste factor: 10% is recommended for spillage.
Enable rebar (optional): Calculate rebar requirements.
Enable cost (optional): Enter prices for cost estimation.
View 3D shape: Drag to rotate, scroll to zoom.
Download report: Get branded PDF or CSV export.

🔢 Formulas & Reference Tables

Volume Formulas

Round: V = π × r² × h
Square: V = w × w × h
Rectangular: V = w × d × h
Hexagonal: V = (3√3 / 2) × s² × h
Octagonal: V = 2(1 + √2) × s² × h

Conversion Factors

1 cubic yard = 27 cubic feet = 0.7646 cubic meters
1 foot = 12 inches = 0.3048 meters
Concrete density: 150 lbs/cu ft

Bag Yields

40 lb bag = 0.30 cubic feet
60 lb bag = 0.45 cubic feet
80 lb bag = 0.60 cubic feet

🏗️ Pour, Cure & Rebar Guide

Pouring Tips

Pour in lifts of 12-24 inches to prevent form blowout.
Vibrate or rod the concrete to remove air pockets.
Pour rate should not exceed 4 feet per hour for narrow columns.

Curing Timeline

Initial set: 2-4 hours
Final set: 6-10 hours
70% strength: 7 days
100% strength: 28 days

Rebar Placement

Minimum 4 bars for round columns.
Maintain minimum 1.5" clear cover from form face.
Use #3 or #4 ties at 6-12" on center.