Walnuts are among the world’s oldest tree foods, valued globally for their nutritional composition and versatility in both sweet and savory dishes. The term “walnut” often refers to the English or Persian walnut (Juglans regia), which dominates commercial markets. Significant variation exists across different cultivars, centered on their physical dimensions. This variation in size, shape, and internal structure influences how walnuts are grown, processed, and used in the kitchen. Consumers must recognize the specific size profiles that define the most common varieties.
Understanding How Walnuts Are Measured
The walnut industry employs a dual system of measurement, categorizing both the intact nut and the shelled kernel. For in-shell walnuts, size is determined by the nut’s diameter, typically sorted through screens. Common commercial classifications include Jumbo (32 millimeters or greater), Large (30 millimeters or more), and Medium (at least 28 millimeters in diameter).
Once shelled, the kernel is graded primarily by its integrity and size. Kernels are sorted into categories using sieves:
- Halves
- Pieces
- Small Pieces
- Crumbs
Halves are the largest category, usually requiring 80% or more of the kernel to remain intact. A crucial metric for commercial growers is the kernel-to-shell ratio, which is the percentage of the total nut weight that is edible kernel. This ratio indicates the yield and efficiency of a variety, where a high percentage signifies a greater return on the raw product.
Size Profiles of Major Commercial Varieties
Modern commercial production centers on the English walnut, using specific cultivars bred for high yield and desirable size characteristics. The Chandler variety is the industry benchmark, known for its large size, typically measuring 34 millimeters or more in diameter. Chandler nuts average 13 to 13.4 grams total weight, with the kernel weighing around 6.5 grams, resulting in a kernel-to-shell ratio of about 50%. This variety is also valued for yielding a high percentage of intact halves with a light kernel color.
The Howard variety, often considered a smaller counterpart to Chandler, offers a similar high yield and light kernel color. Howard nuts are classified as large, weighing between 13 and 15 grams with a kernel yield of around 50%. Another popular cultivar, Tulare, is known for its nearly round shape and slightly higher kernel-to-shell ratio, often reaching 53%. Tulare nuts are large, with average kernel weights reaching 7.1 to 7.5 grams.
In contrast, the Hartley variety is still considered large, weighing 14 to 15 grams, but has a lower kernel yield, typically ranging from 40% to 42%. Hartley nuts have a distinct pointed tip and a thicker shell, historically making them a preferred choice for the in-shell market. These differences illustrate how variations in shell thickness and kernel size translate into differences in commercial value and processing efficiency.
Distinguishing Black Walnuts by Size
The Black Walnut (Juglans nigra) represents a distinct category from English walnut varieties due to its unique physical structure. Black walnuts are native to North America and possess a thick, dense shell that is much harder to crack than the thin, smooth shell of commercial English cultivars. The overall size of the nut can be comparable to some English varieties, often measuring 3 to 4 centimeters in diameter.
Despite the nut’s size, the usable kernel yield of the black walnut is substantially lower. Wild black walnuts typically have a kernel-to-shell ratio ranging from 6% to 14%, though improved cultivars can achieve yields up to 30%. The kernel itself is rounder, smaller, and more difficult to extract in whole pieces, resulting in a higher proportion of smaller fragments and crumbs after processing. This lower yield and the labor-intensive nature of extraction mean the black walnut is valued more for its intense, distinct flavor than for its size or ease of use.
How Walnut Size Affects Kitchen Application
The size and integrity of the walnut kernel directly influence its use in culinary applications. Larger, intact pieces, specifically Halves, are reserved for uses where appearance is important, such as garnishing baked goods, salads, or cheese boards. Consumers often prefer Halves for snacking or trail mixes because of their visual appeal and texture, and this quality usually commands a higher price. The light color and large size of varieties like Chandler make them sought after for these applications.
Conversely, kernel pieces and crumbs, which result from machine cracking or are naturally smaller (like those from Black Walnut), are suited for mixing into batters and crusts. Medium and Small Pieces blend seamlessly into cookies, muffins, and breads, ensuring an even distribution of flavor and crunch. The smallest category, Crumbs, is ideal for applications like oil pressing, where size is irrelevant, or for creating fine textured coatings and specialized confectionery fillings. Recognizing these size distinctions allows cooks and chefs to select the most cost-effective and functionally appropriate walnut product for any recipe.