Corrugated Box Compression Calculator

Estimate box compression test (BCT) strength using the McKee formula and evaluate stacking viability.

Box Specifications & Conditions

Calculation Results

Box Perimeter (Z) -- in
Estimated BCT (McKee) -- lbs
Effective BCT (after derating) -- lbs
Required BCT for Stack -- lbs
Safety Margin -- lbs

About the Corrugated Box Compression (BCT) Calculator

Packaging engineers and supply chain managers can reliably estimate container strength with our corrugated box compression (BCT) calculator. Utilizing the industry-standard McKee formula, this tool processes your Edge Crush Test (ECT) value, board caliper, and box perimeter to predict overall stacking strength. Add a custom safety margin to ensure your cartons withstand warehousing humidity, extended storage, and transport forces.

How it works

  1. Enter the Edge Crush Test (ECT) rating of the corrugated board.
  2. Input the board thickness (caliper) and the total perimeter of the assembled box.
  3. Select an appropriate stacking safety factor based on anticipated storage time, humidity, and pallet patterns.
  4. Review the estimated Box Compression Test (BCT) load capacity to verify it meets your supply chain requirements.

Frequently asked questions

What is the simplified McKee formula for box compression?

The simplified McKee formula estimates BCT using the equation: BCT = 5.87 x ECT x √(Caliper x Perimeter). It assumes a standard regular slotted container (RSC) shape and uniform loading.

Why do I need to apply a safety margin to the BCT?

Laboratory BCT measures the maximum load under ideal, short-term conditions. A safety margin, or multiplier, accounts for real-world strength losses due to high humidity, prolonged storage time, pallet overhang, and vibration during transit.

Does the McKee formula work for all box styles?

No, the standard McKee formula is primarily accurate for Regular Slotted Containers (RSC) with standard proportions. It loses accuracy for very tall, very flat, or highly customized die-cut box styles.

What is the difference between ECT and BCT?

ECT, or Edge Crush Test, measures the edgewise compressive strength of a small piece of the corrugated board itself. BCT, or Box Compression Test, measures the top-to-bottom crushing resistance of the entire formed and sealed box.

References