Plywood is popular for building, making furniture, or crafting whatever you want out of wood, but not all sheets of plywood can hold the same weight. How strong plywood is depends on its size, thickness, material grade, and the distribution of weight.

Factors that Affect Plywood Load Capacities

There are a few factors that dictate how much weight plywood can hold:

1. Length & Width – Bigger sheets disperse weights differently.
2. Thickness — Thicker plywood can support more weight.
3. Material Grade – The stronger the plywood, the higher the grade is.
4. Load Type — Point Loads Do Not Have Capacity Equal to Uniformly Distributed Loads

For the purpose of calculating this load capacity, the following formulas are used.

Formula for Plywood Load Capacity

The general formula for plywood load capacity is:

$C = \frac{L \times W \times T \times S \times F}{1000}$

Where:

• C = Load Capacity (in pounds)
• L = Length of the plywood (in inches)
• W = Width of the plywood (in inches)
• T = Thickness of the plywood (in inches)
• S = Strength Factor (based on material grade)
• F = Load Type Factor (1.0 for uniform load, 0.75 for point load)

Material Strength Factor by Grade

Each plywood grade has a different strength factor:

$\begin{array}{|c|c|} \hline \text{Plywood Grade} & \text{Strength Factor (S)} \\ \hline A \text{ (High Strength)} & 1.5 \\ B \text{ (Medium Strength)} & 1.0 \\ C \text{ (Low Strength)} & 0.5 \\ \hline \end{array}$

Load Type Factor

The way weight is applied to the plywood affects its load capacity:

• Uniform Load (spread across the surface) → Factor = 1.0
• Point Load (applied to a small area) → Factor = 0.75

Example Calculation

Let’s say we have a plywood sheet with the following properties:

• Length = 4 feet (converted to inches: $4 \times 12 = 48$ inches)
• Width = 2 feet (converted to inches: $2 \times 12 = 24$ inches)
• Thickness = 0.75 inches
• Material Grade = B (Strength Factor = 1.0)
• Load Type = Uniform Load (Factor = 1.0)

Step 1: Apply the Formula

$C = \frac{48 \times 24 \times 0.75 \times 1.0 \times 1.0}{1000}$

Step 2: Perform Calculations

$C = \frac{864}{1000}$

$C = 0.864 \text{ lbs}$

Final Answer:

The plywood can support approximately 0.86 pounds under a uniform load condition.