Almond sizes explained: what 18/20, 23/25 and 27/30 actually mean

Last verified: 20 September 2026

The number is a count per ounce, and lower means bigger

The United States Standards for Grades of Shelled Almonds, effective 24 March 1997, sets out two legitimate ways to specify size. Section 51.2113 says size "may be specified in terms of range in count of whole almond kernels per ounce or in terms of minimum, or minimum and maximum diameter."

In the export trade, almost nobody specifies almonds by diameter. Everybody specifies by count. "23/25" means that in a representative sample, between 23 and 25 whole kernels weigh one ounce. So a 18/20 kernel is a big kernel — it only takes eighteen to twenty of them to reach an ounce — and a 34/40 kernel is a small one. The instinct of a new buyer is to read 34/40 as the premium grade because the number is bigger. It is the opposite.

Two details in the standard catch people out on their first contract:

• Doubles and broken kernels do not count. Section 51.2113: "Doubles and broken kernels shall not be used in determining counts." A double kernel is flat on one side because it grew in a shell with a second kernel next to it, and it weighs differently from a single. If your own incoming check counts everything in the scoop, you will get a different number from the handler's certificate and conclude, wrongly, that you were shorted.
• A stated range has no tolerance. Section 51.2114(a) is blunt: "When a range is specified as, for example, '18/20,' no tolerance for counts above or below the range shall be allowed." Diameter specifications get a 10 percent tolerance. Count ranges get none. If you buy 23/25 and the lot averages 25.4, it is not 23/25.

How the count is actually measured

The Almond Board of California's sizing guidance describes the working method: take a sample of either 8 ounces (226.8 g) or 10 ounces (283.5 g), count the whole kernels in it, and divide the count by the sample weight to get kernels per ounce. It is a weight-based measurement expressed as a count, which is why two lots of visually similar almonds can size differently — a denser, better-filled kernel weighs more and therefore lowers the count.

The standard also requires that a lot sold on a count range be uniform, and it defines uniform arithmetically. Section 51.2131: "'Fairly uniform in size' means that, in a representative sample, the weight of 10 percent, by count, of the largest whole kernels shall not exceed 1.70 times the weight of 10 percent, by count, of the smallest whole kernels." That 1.70 figure is the one to quote back at a supplier who sends you a lot that averages inside the range but visibly contains two populations of almond.

The count ranges the trade actually uses

Section 51.2113 lists the ranges "commonly used," and permits others provided the kernels are fairly uniform. The listed ranges are:

The count ranges in the left column are the ones named in §51.2113. The applications in the right column are ordinary trade practice and appear nowhere in the standard — a handler may well ship 18/20 into a bakery and 27/30 into a retail bag, and there is nothing wrong with either.

Variety changes what a size is available in

Size and variety are not independent. The Almond Board's technical guide for California almonds groups varieties into three marketing classifications — Nonpareil type (Nonpareil, Independence), California type (Aldrich, Carmel, Monterey, Price, Sonora, Wood Colony and others), and Mission type (Butte, Padre and others). The USDA standard recognises the same convention: §51.2116(b) provides that a lot marked "California" may include any combination of blanchable varieties within the California marketing classification, plus up to 25 percent by weight of Nonpareil or similar types.

Practically, that means a request for "18/20 Mission" is a harder ask than "18/20 Nonpareil," and a request for "27/30 Nonpareil" is an odd one — you are paying the Nonpareil premium for a size where the variety's advantages (clean, smooth, blanchable, uniform kernel) matter least. Tell a supplier the application alongside the size and a good one will push back on the variety.

What each size is worth, and why nobody will publish that

There is no fixed price ladder between sizes, and any supplier who quotes you one from a chart is quoting you a number they may not honour. What exists is a spread, and the spread moves for a structural reason: the size distribution of a California crop is set in the orchard, months before anyone sells anything. Water, heat, crop load and variety mix determine how much of a given year's tonnage lands at 18/20 and how much lands at 27/30. Demand, meanwhile, is set by what confectioners, retailers and manufacturers need — which does not move in step with what the trees produced.

So in a year with a large crop of small kernels, the big counts carry an unusually wide premium; in a year that sized up well, the premium narrows and the small counts can get tight instead. The gap between 23/25 and 18/20 in one crop year tells you very little about the gap in the next.

The three things to put on your enquiry

A size on its own does not let anyone quote you. The minimum useful specification is variety class + count range + grade, plus pack and destination:

• Variety class — Nonpareil, California or Mission (see above).
• Count range — for example 23/25, remembering that the range carries no tolerance.
• Grade — U.S. Select Sheller Run, U.S. Fancy, U.S. Extra No. 1 and the rest are separate from size and control defects, not dimensions. What SSR, Fancy and Extra No. 1 actually mean covers that in full.
• Pack and destination — 25 lb or 50 lb export carton or 2,000 lb tote; the port you want it landed at; the incoterm you want quoted.

Get those five things into the first email and a written quotation is a one-day job rather than a three-email negotiation about what you meant.

Sources

• USDA Agricultural Marketing Service, United States Standards for Grades of Shelled Almonds, effective 24 March 1997 — §51.2113 size requirements, §51.2114 tolerances for size, §51.2116 similar varietal characteristics, §51.2131 fairly uniform in size. ams.usda.gov
• Almond Board of California, Understanding the Process Used to Determine Sizing, September 2023 — sample weights and the count-per-ounce calculation. almonds.org
• Almond Board of California, Guide to California Almonds technical poster — variety marketing classifications. almonds.org

More from this series

• Almond grades: SSR, Fancy, Extra No. 1
• Aflatoxin limits by market
• The export document set
• HS codes for tree nuts