Janka Hardness Scale

When choosing wood for flooring, furniture, cabinetry, or specialty woodworking projects, durability matters. Some wood species dent easily while others resist years of heavy traffic. The Janka Hardness Scale is the most widely recognized system for measuring that durability. It gives woodworkers and buyers an objective way to compare the hardness of hundreds of domestic and exotic lumber species.

This complete guide explains how the Janka test works, why hardness matters, how to use the scale when selecting wood, and how scores differ across species. You will also find a detailed breakdown of factors that influence hardness and practical tips for choosing the right wood for your project.

By the end, you will understand the Janka Hardness Scale with expert clarity and be able to make confident decisions about the wood you choose.

What Is the Janka Hardness Scale

The Janka Hardness Scale measures how much force is required to embed a solid steel ball into a piece of wood. The ball is 0.444 inches in diameter. The test measures the amount of pounds force needed to push the ball halfway into the wood’s surface.

A higher number indicates a harder and more dent resistant wood. A lower number indicates a softer wood that may show wear more easily.

The scale is widely used in the United States and internationally. Flooring manufacturers, woodworkers, builders, and millworkers rely on Janka ratings to compare products and select the right materials for function and longevity.

Table of Janka Hardness Ratings

Below is the complete list provided, arranged exactly as given, showing the broad range of species from soft to extremely dense.

Important Accuracy Notes

• Janka ratings are averages and can vary slightly by source, moisture content, and species variation.

• Burls, figured, quilted, or quarter-sawn woods do NOT have separate Janka values, they share the base species rating.

• Exotic woods often have ranges, not single fixed numbers.

Why the Janka Test Matters

Wood hardness is not the only property that affects durability, but it is one of the most important. Here is why the Janka test is valuable.

1. It Predicts Dent Resistance

Harder woods resist dents from furniture legs, dropped objects, foot traffic, and general impacts. Soft woods mark more easily.

2. It Helps Construct Long Lasting Flooring

Flooring companies use Janka ratings to determine which species perform well in homes, commercial spaces, and high traffic areas.

3. It Guides Woodworkers in Choosing the Right Species

Some projects need softer woods for easy carving and shaping. Others need harder woods for stability and wear resistance.

4. It Helps Compare Domestic and Exotic Woods

The Janka Hardness Scale creates a level field. Wood from North America, South America, Africa, Asia, and Europe can be directly compared.

How the Janka Test Works

The Janka test follows a consistent procedure to ensure fair comparisons.

Step 1. A piece of wood is prepared

The sample must be free of knots and defects. The grain orientation is also controlled because hardness varies depending on whether the grain is parallel or perpendicular to the surface.

Step 2. A 0.444 inch steel ball is placed against the surface

This specific diameter is used globally.

Step 3. A machine applies steady pressure until the ball reaches half its own diameter

The force required to push the ball halfway in is measured. This number becomes the Janka rating.

Step 4. Results are recorded in pounds force

This allows easy comparison between species.

Although simple in concept, this standardized process produces reliable and repeatable results that professionals depend on.

Understanding the Range of Janka Hardness Values

The Janka scale spans a wide range. At the lower end, very soft woods like Buckeye Burl rate around 350 pounds force. On the higher end, extremely dense species like Genuine Lignum Vitae measure more than 4300 pounds force.

Most commonly used hardwood flooring species fall between 900 and 2000 pounds force.

Below is an overview of what different ranges typically indicate.

0 to 600: Very Soft Woods

Examples include Buckeye Burl, Aspen, and Basswood. These woods are ideal for carving and lightweight projects but dent extremely easily.

600 to 1000: Soft to Moderate Hardness

Spanish Cedar and Peruvian Walnut fall into this category. Suitable for furniture, trim, or decorative elements.

1000 to 1500: Common Hardwoods

Walnut, Teak, Red Oak, Birch, Maple, and Koa appear in this range. Many flooring and furniture species fall here because they balance workability and durability.

1500 to 2000: Hard and Durable Woods

Sapele, Honey Locust, Merbau, Padauk, and Wenge are harder and more resistant to wear. Many exotic flooring options fall into this range.

2000 to 3000: Very Hard Woods

Bubinga, Purpleheart, Jatoba, Osage Orange, and Cocobolo are extremely dense, wear resistant, and challenging to work with.

3000 and Above: Extremely Hard and Rare Woods

Ebony, Angelim Pedra, African Blackwood, and Lignum Vitae are among the hardest woods in the world. These are prized for specialty work such as instrument making, tool handles, and fine craft pieces.

What Influences a Wood’s Janka Hardness Rating

Several natural factors determine how hard a species of wood is.

1. Density

The heavier and denser the wood, the harder it tends to be. Density is influenced by how the tree grows, the rate of growth, and the structure of its cells.

2. Moisture Content

Woods tested at higher moisture content tend to be softer. Kiln dried woods usually test harder and more consistently.

3. Grain Direction

Testing across the grain produces a higher hardness number than testing along the grain.

4. Natural Oils and Extractives

Some exotic woods contain resins and oils that increase density and hardness. Examples include teak, ipe, and many rosewoods.

5. Species and Growth Environment

Trees grown in tropical climates often have higher density due to slow, steady growth.

How to Use the Janka Scale When Choosing Wood

The scale is not only for experts. Anyone selecting wood can benefit from knowing how to use these numbers.

For Flooring

Harder is generally better. A wood under 1000 pounds force may dent in busy homes. Popular choices include:

• Red Oak at 1220
• White Oak at 1335
• Hard Maple at 1450
• Hickory at 1820
• Jatoba at 2690
• Ipe at 3510

Higher hardness improves longevity and reduces visible wear.

For Furniture

Furniture makers balance hardness with workability. Woods like walnut, cherry, and maple are favored because they are strong yet still workable.

For Cabinets and Millwork

Hardness may matter less than stability, grain, and appearance. Moderate woods like birch and oak work well.

For Carving and Turning

Soft woods like basswood carve beautifully but cannot withstand heavy wear. Exotic turning woods like cocobolo and African blackwood offer exceptional hardness for fine detail.

For Outdoor Projects

Hardness alone does not determine weather resistance. Oils, decay resistance, and stability also matter. Ipe and teak excel because they combine high hardness with natural resistance to weather and insects.

Pros and Cons of Using the Janka Hardness Scale

Although the scale is widely used, it has limitations.

Benefits

• Provides an objective comparison
• Helps match wood hardness to project requirements
• Has a standardized testing method
• Represents dent resistance accurately
• Widely accepted across woodworking industries

Limitations

• Does not measure overall durability
• Does not predict scratch resistance
• Does not account for finish quality
• Does not represent stability or movement
• Some natural variation exists within species

For example, a very hard wood that reacts poorly to humidity may still warp or crack even if it resists dents.

Domestic vs Exotic Woods on the Janka Scale

Domestic North American woods typically fall between 400 and 1800 pounds force. Exotic species often test much higher due to increased density.

Here is a general comparison.

Domestic Woods

• Douglas Fir: soft
• Pine: varies based on species
• Cherry: moderate
• Red Oak: widely used and reliable
• Hard Maple: harder and more durable
• Hickory: one of the hardest domestic choices

Exotic Woods

• Sapele, Padauk, and Zebrawood: medium hard
• Purpleheart and Bubinga: very hard
• Jatoba and Cumaru: extremely hard and dense
• Ebony and Lignum Vitae: among the hardest woods anywhere

Exotic hardwoods often require stronger tools, more frequent sharpening, and additional time to mill or finish. Their hardness brings both benefits and challenges.

Janka Hardness and Wood Flooring Performance

One of the most common uses of the Janka scale is the evaluation of hardwood flooring. Here are considerations that homeowners and designers should know.

How Hardness Affects Flooring

• Hardwoods resist dents from pets and heavy furniture
• Harder floors show fewer wear lines over time
• They may create more noise if not installed with proper underlayment
• Very hard woods can be difficult to sand or refinish

Engineered vs Solid

The Janka rating applies to the wood wear layer itself. Engineered floors that use a veneer of a hard wood will reflect that hardness on the walking surface.

Finishes Also Affect Durability

Even a soft wood with a strong aluminum oxide finish can outperform an unfinished harder species. Finish technology plays a large role in real world performance.

Tips for Selecting the Right Wood Based on Janka Hardness

Choosing the right hardness level depends on the purpose of the wood.

For Homes With Children or Pets

Choose woods above 1300 for better dent resistance. Solid choices include white oak, hard maple, hickory, and many exotics.

For High End Furniture

Aim for 900 to 1500. These species offer strength while allowing easier shaping and machining.

For Decorative or Artistic Woodworking

Consider stability, figure, and appearance as much as hardness. Burl, spalted pieces, and figured woods may be softer but more visually striking.

For Builders and Contractors

Balance cost, durability, and availability. Domestic woods remain the most practical choice for large scale applications.

For Instrument Makers

Extremely hard woods like ebony and African blackwood offer tonal qualities and durability unmatched by softer species.

Common Myths About the Janka Hardness Scale

Because the scale is widely referenced, it is often misunderstood. Here are some common misconceptions.

Myth 1. Harder always means better

This is not always true. Very hard woods may crack if mishandled, require specialized tools, or be difficult to install.

Myth 2. Janka ratings predict scratch resistance

Scratches often come from grit or debris and are influenced by finish quality, not hardness.

Myth 3. All boards of the same species have identical hardness

Nature varies. Climate, soil, tree age, and growth speed all influence hardness.

Myth 4. The scale measures durability

Hardness is only one part of durability. Stability, finish, density, and resistance to moisture all matter.

Conclusion

The Janka Hardness Scale is one of the most valuable tools in woodworking and flooring selection. Whether you are a homeowner choosing hardwood floors, a contractor selecting durable materials, or a woodworker deciding which species suits your next project, the Janka rating provides a clear and reliable reference point.

It does not tell the entire story of how a wood will perform, yet it provides vital information about dent resistance and density. When combined with other factors such as grain stability, finish quality, and environmental performance, the Janka scale helps guide smarter and more informed decisions.

Knowing how to interpret Janka hardness ratings allows you to choose wood that looks beautiful, performs well, and lasts for many years. With the right knowledge, you can select the perfect balance of hardness, aesthetics, and practicality for any project.