Compression Strength Paper Testing Methods

There are two ways of measuring the compression strength, the Ring Crush Test (RCT) and the Short-Span Compressive Test (SCT).

Apply these formulas directly in our calculator below

Ring Crush Test (RCT) Calculator

How this works
This calculator estimates the Ring Crush Test (RCT CD) value from the Short Span Compressive Test (SCT CD) value.

- Equation 1: RCT CD = 120 × SCT CD – 97
- Equation 2: RCT CD = 95 × SCT CD

Select the equation that best fits your test method or local guidelines.

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FAQ

Compression strength refers to a paper’s ability to resist crushing forces. It’s a key measure of packaging performance, ensuring boxes can stack and transport safely without collapsing.

The Short Span Compression Test (SCT) measures the compressive strength of paper over a short span. It’s used because it provides consistent results and avoids buckling, giving a reliable indicator of paper performance. 

The Ring Crush Test (RCT) measures compression strength using a longer span of paper that can buckle more easily. It’s been largely replaced by the SCT because SCT results are more consistent and less prone to buckling variations. 

Compression strength can be estimated using formulas that relate SCT to RCT values. Common equations include RCT CD = 120 x SCT CD - 97 or RCT CD = 95 x SCT CD. Always check with your supplier for the best equation for your specific product. 

RCT stands for Ring Crush Test, a standard test for measuring the compressive strength of paperboard.

Yes, we now offer an interactive calculator that allows you to estimate RCT values from SCT results, using the recommended formulas. 

The compressive strength of a corrugated box refers to its ability to withstand crushing forces during stacking and transportation. It’s influenced by factors like material type, flute profile, and construction, and can be estimated using standard tests like RCT and SCT.