Rarity Scales

by Dan Gosling, Edmonton Numismatic Society

Over the years different scales have been used to describe the rarity of estimated, or known surviving examples. This table attempts to compile this information at one location to facilitate comparisons between different scales*.

Adams & Woodin Sheldon Judd Bowers Reynolds Heikkila Fibonacci Bowers-Fivaz-Stanton
Low High Low High Low High Low High Low High Low High Low High Low High
R-24 4,194,305 8,388,608 20,000,001 50,000,000 8,388,609 16,777,216 75,025 121,392 URS-24 4,000,000 7,999,999
R-23 2,097,153 4,194,304 10,000,001 20,000,000 4,194,305 8,388,608 46,368 75,024 URS-23 2,000,000 3,999,999
R-22 1,048,577 2,097,152 5,000,001 10,000,000 2,097,153 4,194,304 28,657 46,367 URS-22 1,000,000 1,999,999
R-21 524,289 1,048,576 2,000,001 5,000,000 1,048,577 2,097,152 17,711 28,656 URS-21 500,000 999,999
R-20 262,145 524,288 1,000,001 2,000,000 524,289 1,048,576 10,946 17,710 URS-20 250,000 499,999
R-19 131,073 262,144 500,001 1,000,000 262,145 524,288 6,765 10,945 URS-19 125,000 249,999
R-18 65,537 131,072 200,001 500,000 131,073 262,144 4,181 6,764 URS-18 65,000 124,999
R-17 32,769 65,536 100,001 200,000 65,537 131,072 2,584 4,180 URS-17 32,000 64,999
R-16 16,385 32,768 50,001 100,000 32,769 65,536 1,597 2,583 URS-16 16,000 31,999
R-15 0 1 8,193 16,384 20,001 50,000 16,385 32,768 987 1,596 URS-15 8,000 15,999
R-14 2 3 4,097 8,192 10,001 20,000 8,193 16,384 610 986 URS-14 4,000 7,999
R-13 4 5 2,049 4,096 5,001 10,000 4,097 8,192 377 609 URS-13 2,000 3,999
R-12 6 8 1,025 2,048 2,001 5,000 2,049 4,096 233 376 URS-12 1,000 1,999
R-11 9 12 513 1,024 1,001 2,000 1,025 2,048 144 232 URS-11 500 999
R-10 13 15 1 3 257 512 501 1,000 513 1,024 89 143 URS-10 250 499
R-9 16 20 4 6 129 256 201 500 257 512 55 88 URS-9 125 249
R-8 21 25 1 3 7 12 65 128 101 200 129 256 34 54 URS-8 65 124
R-7 26 35 4 12 13 20 33 64 51 100 65 128 21 33 URS-7 33 64
R-6 36 50 13 30 21 30 17 32 21 50 33 64 13 20 URS-6 17 32
R-5 51 75 31 75 31 75 9 16 11 20 17 32 8 12 URS-5 9 16
R-4 76 100 76 200 76 200 5 8 6 10 9 16 5 7 URS-4 5 8
R-3 101 300 201 500 201 500 3 4 4 5 5 8 3 4 URS-3 3 4
R-2 301 500 501 1,250 501 1,250 2 2 2 3 3 4 2 2 URS-2 2 2
R-1 501 800 1,251 1,251 1 1 1 1 2 2 1 1 URS-1 1 1
R-0 1 1 URS-0 0 0

*source: Q. David Bowers, Coins & Collectors (The Numismatist, June 1992) pages 790-794; Q. David Bowers, Coins & Collectors (The Numismatist October 1992) pages 1359-1360, Letters, (The Numismatist October 1992) pages 1432-1434.