Hardwood Hardness: The Janka Scale Explained

The Janka hardness test measures how much force it takes to press a 0.444-inch steel ball halfway into a piece of wood. The higher the number, in pounds-force (lbf), the better the wood resists dents. Among common flooring species, hickory is hardest at roughly 1,800 to 1,900 lbf, followed by hard maple (1,450), white oak (1,360), ash (1,320), red oak (1,290), walnut (1,010) and cherry (950). Janka predicts dent resistance, not scratch resistance; the finish matters more for scratches.

How the Janka test works

A testing machine pushes a steel ball 0.444 inch in diameter into the side of a wood sample until half the ball is embedded, and records the force needed. The standard reference values published by the USDA Forest Products Laboratory are for clear wood with no defects at 12 percent moisture content. Real floorboards vary: density changes from tree to tree and even within one board, so treat Janka figures as averages for comparing species, not exact values for a specific floor.

Janka ratings for common flooring species

Values are side hardness at 12 percent moisture from the USDA Wood Handbook, except European oak, which comes from The Wood Database. Different sources test different samples, so you'll see figures vary by a few percent. Published numbers for European oak run somewhat lower than for American white oak, though in daily use the finish and wear layer have a bigger effect than that gap.

What hardness tells you, and what it doesn't

Dents: this is what Janka measures. A dropped pan, a chair leg or a high heel will dent walnut more easily than hickory. All hardwood will dent with enough force.

Scratches: most everyday scratches are in the finish, not the wood. A matte or low-sheen finish and a textured surface such as wire-brushed hide scratches far better than a glossy, smooth floor, whatever the species.

Color and grain: busy grain and color variation, as in hickory, camouflage wear. Even, light grain, as in maple, shows more.

Stability: hardness says nothing about how much a board moves with humidity. Engineered construction, a real hardwood wear layer on a stable core, is what improves stability, especially over concrete slabs.

Hardness and engineered hardwood

On an engineered floor, the species of the top wear layer sets the surface hardness, so an engineered hickory dents about like solid hickory. The core and the overall construction affect how the floor feels underfoot and how well it handles impacts. The wear layer's thickness doesn't change the Janka rating, but it does determine how much the surface can be sanded in the future.

Choosing by household

• Large dogs, kids and heavy traffic: a harder species such as hickory or maple, or oak in a matte or wire-brushed finish.
• A light, natural look with good durability: white oak, including European white oak planks in natural or wire-brushed finishes.
• Rich color in quieter rooms: walnut or cherry, accepting that they show dents sooner.
• Any home: felt pads on furniture, trimmed pet nails, and no stiletto heels or sports cleats on the floor go further than a few hundred points of Janka.

Species is one choice among many. Our hardwood flooring guide and showroom selection covers construction, plank width and finishes too, and when you're ready, see how our crews install hardwood.

See the boards before you decide

Feel the difference between species side by side. Visit our showroom at 21030 Victory Blvd, Woodland Hills, or book an in-home consultation. We bring flooring samples to your home. Call (818) 963-0878. Glamour Flooring is a family business serving the area since 2007, a licensed flooring contractor (CSLB #1005283) that installs the floors we sell.