Column Form Calculator

Calculate column form plywood area, clamp spacing, and concrete volume.

Column width (in)

Column depth (in)

Column height (ft)

Concrete unit weight (pcf)

Clamp/yoke capacity (lbs)

Tab to move between fields

Max pressure at base (psf)

1,800

Max pressure (psi)12.5

Plywood contact area (sf)96

4×8 plywood sheets3

Concrete volume (cy)1.78

Min clamp spacing (in)13

Total clamps needed13

How to Use This Calculator

Enter the Column Width, Column Depth in inches, and Column Height in feet.
Enter the Concrete Unit Weight (typically 145–150 pcf) and Clamp Safe Working Load.
Review Max Lateral Pressure at Base in psf — this governs clamp spacing design.
Check Minimum Clamp Spacing at the base and Total Clamps needed for the full column height.
Use Concrete Volume in cubic yards to coordinate pour scheduling and truck ordering.

How the result changes with Column height (ft)

Column width (in): Width of the column cross-section in inches.
Column depth (in): Depth of the column cross-section in inches.
Column height (ft): Floor-to-floor column height.
Concrete unit weight (pcf): Unit weight of concrete. Normal weight: 145-150 pcf.
Clamp/yoke capacity (lbs): Safe working load of each column clamp or yoke.

Max pressure at base (psf): Full hydrostatic lateral pressure at the column base.
Max pressure (psi): Lateral pressure at base in pounds per square inch.
Plywood contact area (sf): Total form contact area for all four sides.
4×8 plywood sheets: Number of 4×8 ft plywood sheets needed (rounded up).
Concrete volume (cy): Volume of concrete in cubic yards for one column.
Min clamp spacing (in): Minimum clamp spacing at the base where pressure is highest.
Total clamps needed: Number of clamps/yokes using minimum spacing (conservative).

Identify Input Parameters
4 parameters
Column width (in) = 24, Column depth (in) = 24, Column height (ft) = 12, Concrete unit weight (pcf) = 150 = 5 input(s) provided
Calculate Max pressure at base
Max pressure at base = concreteWeight * columnHeight
1800 = 1800
Calculate Max pressure
Max pressure = maxPressurePsf / 144
12.5 = 12.5
Calculate Plywood contact area
Plywood contact area = perimeterFt * columnHeight
96 = 96