What is the Janka Hardness Test?


    Wondering what the best type of hardwood is for your indoor / outdoor floor, or deck?  First you should consider where the product is going.  If it’s going into a kids playroom or room that is often used you’ll want hardwood that is in actually hard.  To calculate the hardness of a piece of a hardwood, the Janka hardness test is used.  This industry standard test’s purpose is to measure the resistance of wood to denting and extensive wear.  It works by measuring the force required to embed a .444 inch steel ball into the wood to half the ball’s diameter.  How much force the ball needs to be embedded into your hardwood will show you if your hardwood is easily dented.

The hardness of the wood also varies on the direction of the wood grain.  Testing on the surface of a plank perpendicular to the grain is known as side hardness.  Testing on the cut surface of a stump is known as end hardness.  The most common reason for testing is to determine whether the species of hardwood you have is a suitable use of flooring for your home.


Above is the list showing the hardness of various hardwoods.  If you’re redoing your hardwood floors or renovating a deck remember to plan accordingly.  If you have small children that enjoy dropping anything and everything they get their hands on then you’re going to want a harder type of flooring.  The softer the wood, the more it will wear down while the harder the wood the longer it takes to wear down.


        As you might expect, Ipe is exceptionally strong. It outranks Teak, Oak, and many other hardwoods. It’s also 8 times harder than Redwood, a fact that surprises many except those who own a deck or floor made of Ipe.

Get your free Ipe decking quote directly from the mill. Contact IpeDepot.com today.

What Ipe’s Hardness & Strength Mean for You

Ipe is famous primarily because it is one of the hardest and strongest woods in the world.  In fact, Ipe decking exceeds all existing code requirements for exterior constructions.  Here are the official stats:

Hardness: ASTM-D143 tested, approximately 7x harder than Cedar, Janka Side Hardness 3,680 lb

Strength: ASTM-D143 tested, approximately 3x stronger than Cedar, bending strength 22,560 psi

Before we go any further, you may be wondering what the difference is between these two terms.  Hardness is a material’s resistance to indentation, scratching, and abrasion.  Strength is a measure of how much stress a material can withstand without rupturing.

These two traits are closely related, since the same atomic-level characteristics play a role in both.  Although this is not a hard and fast rule and there are exceptions, generally, making a material stronger will also make it harder.

The next obvious question is this: how do these characteristics help you?

Strength can be defined more practically as the thing that prevents deck boards from breaking—one of the main reasons it is so often used in major public attractions across the country, where safety is a huge concern.

A hard decking material like Ipe will keep your deck from accumulating dents and scratches, allowing it to look beautiful for the entirety of its life.  It also makes Ipe impossible for termites and other insects to eat—just imagine if you tried to take a bite out of a rock.  This extends Ipe’s lifespan long past other softer woods.