Dynamic coefficient of friction, or DCOF, is a measure of how much grip a surface has while something is moving across it. Higher numbers mean more traction. Flooring is tested wet with a standard device to compare slip resistance. It’s the main measurement used in the U.S. slip standard for hard floors.
What a DCOF Rating Means for Slip Safety
DCOF measures grip while your foot is already sliding, which is the moment a slip happens. It’s the ratio between the force needed to move one surface over another and the pressure between them. In plain terms, a higher number means the floor fights back harder when your shoe starts to skid.
The number you’ll see most is 0.42. Under the U.S. standard, ANSI A326.3, hard floors meant for level interior spaces expected to be walked on when wet should test at 0.42 or higher. Outdoor and pool areas call for more, with a minimum of 0.60.
A DCOF rating is a comparison tool, not a promise. Lab numbers shouldn’t be taken as a sign of whether a slip can occur, because spills, oil, cleaning habits, and footwear all change real-world grip.
Dynamic Coefficient of Friction FAQ
What is the difference between DCOF and SCOF?
DCOF measures grip while a surface is already moving, like a foot mid-slide. SCOF, or static coefficient of friction, measures the force needed to start movement. DCOF is the measurement the current U.S. hard-floor standard uses.
What is a good DCOF rating?
For indoor floors that may get wet, 0.42 or higher is the baseline. For outdoor areas and pool decks, look for 0.60 or higher. Higher is grippier, but a rough floor is also harder to clean.