How Rare Is It?

Reknowned Numismatist Q David Bowers developed a Universal Rarity Scale years ago.  PCGS has also developed a rarity scale.  Using the surviving population, both scales can be applied to any coin series.  It's important to note that both scale are arbitrary, as "Rare" is not particularly well defined.  Nonetheless, these scales can be handy.  Below I have them side by side to simplify conversion between the scales.

Bowers' Universal Rarity Scale		PCGS Rarity Scale
Pop	Scale	Pop	Scale	Descriptive
0	URS-0	0	10.1	None Known
1	URS-1	1	10	Unique
2	URS-2	2	9.9	Ultra Rare
3 to 4	URS-3	3 to 4	9.8	Ultra Rare
5 to 8	URS-4	5 to 6	9.7	Ultra Rare
9 to 16	URS-5	7 to 9	9.6	Ultra Rare
		10 to 12	9.5	Ultra Rare
		13 to 14	9.4	Ultra Rare
		15 to 16	9.3	Ultra Rare
17 to 32	URS-6	17 to 18	9.2	Ultra Rare
		19 to 20	9.1	Ultra Rare
		21 to 25	9	Ultra Rare
		26 to 30	8.9	Extremely Rare
33 to 64	URS-7	31 - 35	8.8	Extremely Rare
		36 - 40	8.7	Extremely Rare
		41 - 45	8.6	Extremely Rare
		46 - 50	8.5	Extremely Rare
		51 - 60	8.4	Extremely Rare
65 to 125	URS-8	61 - 70	8.3	Extremely Rare
		71 - 80	8.2	Extremely Rare
		81 - 90	8.1	Extremely Rare
		91 - 100	8	Extremely Rare
		101 - 110	7.9	Very Rare
		111 - 120	7.8	Very Rare
126 to 250	URS-9	121 - 130	7.7	Very Rare
		131 - 140	7.6	Very Rare
		141 - 150	7.5	Very Rare
		151 - 160	7.4	Very Rare
		161 - 170	7.3	Very Rare
		171 - 180	7.2	Very Rare
		181 - 190	7.1	Very Rare
		191 - 200	7	Very Rare
		201 - 210	6.9	Rare
		211 - 220	6.8	Rare
		221 - 240	6.7	Rare
251 to 500	URS-10	241 - 260	6.6	Rare
		261 - 280	6.5	Rare
		281 - 300	6.4	Rare
		301 - 350	6.3	Rare
		351 - 400	6.2	Rare
		401 - 450	6.1	Rare
		451 - 500	6	Rare
501 to 1000	URS-11	501 - 550	5.9	Rare
		551 - 600	5.8	Rare
		601 - 650	5.7	Rare
		651 - 700	5.6	Rare
		701 - 750	5.5	Rare
		751 - 800	5.4	Rare
		801 - 850	5.3	Rare
		851 - 900	5.2	Rare
		901 - 950	5.1	Rare
		951 - 1000	5	Rare
1001 to 2000	URS-12	1001 - 1250	4.9	Very Scarce
		1251 - 1500	4.8	Very Scarce
		1501 - 1750	4.7	Very Scarce
		1751 - 2000	4.6	Very Scarce
2001 to 4000	URS-13	2001 - 2500	4.5	Very Scarce
		2501 - 3000	4.4	Very Scarce
		3001 - 3500	4.3	Very Scarce
		3501 - 4000	4.2	Very Scarce
4001 to 8000	URS-14	4001 - 4500	4.1	Very Scarce
		4501 - 5000	4	Very Scarce
		5001 - 5500	3.9	Very Scarce
		5501 - 6000	3.8	Very Scarce
		6001 - 6500	3.7	Very Scarce
		6501 - 7000	3.6	Very Scarce
		7001 - 7500	3.5	Very Scarce
		7501 - 8000	3.4	Very Scarce
8001 to 16000	URS-15	8001 - 8500	3.3	Very Scarce
		8501 - 9000	3.2	Very Scarce
		9001 - 9500	3.1	Very Scarce
		9501 - 10,000	3	Very Scarce
		10,001 - 15,000	2.9	Scarce
16001 to 32000	URS-16	15,001 - 20,000	2.8	Scarce
		20,001 - 30,000	2.7	Scarce
32001 to 65000	URS-17	30,001 - 40,000	2.6	Scarce
		40,001 - 50,000	2.5	Scarce
		50,001 - 60,000	2.4	Scarce
65001 to 125000	URS-18	60,001 - 70,000	2.3	Scarce
		70,001 - 80,000	2.2	Scarce
		80,001 - 90,000	2.1	Scarce
		90,001 - 100,000	2	Scarce
125001 to 250k	URS-19	100,001 - 200,000	1.9	Scarce
250k to 500k	URS-20	200,001 - 300,000	1.8	Common
		300,001 - 400,000	1.7	Common
500k to 1M	URS-21	400,001 - 500,000	1.6	Common
		500,001 - 600,000	1.5	Common
		600,001 - 700,000	1.4	Common
		700,001 - 800,000	1.3	Common
		800,001 - 900,000	1.2	Common
		900,001 - 1,000,000	1.1	Common
		over 1,000,000	1	Very Common