The size requirements in order to sell a walnut log can depend on various factors including local regulations, market demand, and individual buyer preferences. Generally speaking, larger logs tend to have higher value due to the greater amount of usable lumber they contain. However, there are typically minimum diameter or length requirements set by buyers or sawmills based on their log handling equipment capabilities and processing needs. In some cases, smaller logs may also find buyers who specialize in unique projects or crafts that do not require large dimensions. It's advisable to contact local buyers or sawmills in advance to understand their specific requirements when considering selling walnut logs.