Oak is generally harder than ash. This conclusion is based on the Janka hardness scale, which measures the resistance of wood to indentation. According to the Janka scale, oak wood typically ranges from 1,300 to 1,450 pounds-force (lb-f) on average, while ash wood generally falls between 900 and 1,300 lb-f. The higher the Janka rating, the harder the wood. Oak's higher rating indicates it is more resistant to dents, scratches, and wear, making it a preferred choice for furniture, flooring, and construction applications. This difference in hardness is due to oak's denser grain structure and higher lignin content, which provides greater strength and durability.