Fancy Serial Numbers: check yours in seconds
12 patterns · odds counted, not estimated
Every US banknote carries eight digits. A handful of the hundred million possible combinations are collected in their own right — and this tells you, for free and without a valuation, exactly which ones yours hits and how few notes share it.
What makes a serial number “fancy”
Nothing about the note itself. A fancy serial number is a pattern in the digits that collectors have agreed to care about: eight of the same digit, a number that reads the same backwards, a block that repeats, a run that climbs from 1 to 8. The paper, the ink and the printing are identical to every other note from that run. What is scarce is the arrangement, and scarcity is something you can count exactly.
So that is what this page does. For each pattern you will find how many of the 99,999,999 possible serial numbers match it — not an estimate, not a dealer’s impression, a count. A solid has nine matches in the entire numbering system. Bookends have a million. Those two facts belong in the same table precisely because they are so far apart.
The twelve patterns, rarest first
| Pattern | Example | Matching serials | Odds | What it is |
|---|---|---|---|---|
| Ladder | 12345678 | 6 | 1 in 16,666,667 | The digits run straight up or straight down with no gaps. 12345678 and 87654321 are the two classics; 01234567, 23456789, 76543210 and 98765432 complete the set of six. |
| Solid | 33333333 | 9 | 1 in 11,111,111 | All eight digits the same. There is one per digit and no tenth, because 00000000 is never printed. |
| Double quad | 11112222 | 90 | 1 in 1,111,111 | Four of one digit, then four of another. Ten choices for the first block, nine for the second. |
| Super repeater | 12121212 | 99 | 1 in 1,010,101 | A two-digit block printed four times over. Every super repeater is also a repeater. |
| Low serial | 00000007 | 100 | 1 in 1,000,000 | 00000001 to 00000100 — the first hundred notes numbered in their run. Under 00000010 is scarcer still. |
| High serial | 99999995 | 100 | 1 in 1,000,000 | 99999900 to 99999999, the last hundred before the counter runs out. |
| Radar | 12344321 | 9,999 | 1 in 10,001 | It reads the same backwards as forwards. A super radar — one digit wrapped around six identical ones, like 18888881 — is one of only 90. |
| Repeater | 12341234 | 9,999 | 1 in 10,001 | The first four digits repeat as the last four. |
| Binary | 10011001 | 11,430 | 1 in 8,749 | Only two different digits in the whole serial. The 0-and-1 ones are the set collectors ask for by name. |
| Birthday | 12251999 | 73,049 | 1 in 1,369 | It reads as a real calendar date in MM/DD/YYYY, with the year between 1900 and 2099. |
| Trinary | 12211220 | 695,520 | 1 in 144 | Three different digits and no more. |
| Bookends | 47000047 | 999,999 | 1 in 100 | The first two digits and the last two are the same pair. Listed because collectors list it — on its own it is not scarce. |
A serial can hit several at once, and most of the interesting ones do. 10101010 is binary, a repeater, a super repeater and a pair of bookends. 12211221 is a radar and a repeater, which is rarer than being either. The checker above lists everything it finds and puts the scarcest first.
Why the birthday window stops at 1900
A birthday note is a serial that reads as a date: 12251999 is Christmas Day 1999. We only count one when the year lands between 1900 and 2099, and it is worth saying why, because it changes the answer. Without that window, 12121212 is a perfectly valid 12 December 1212 and 11112222 is 11 November 2222 — real calendar dates, nobody’s birthday. Counting them turns the pattern from 73,049 serials into 3,652,425, hands a medal to one note in every twenty-seven, and makes the whole page mean less. The narrower rule is the honest one.
What this page will not do
It will not tell you what your note is worth, and you should be wary of any page that does from a serial number alone. Two notes with the same radar serial can be worth an order of magnitude apart: one crisp and uncirculated, the other folded in a wallet for fifteen years. Those are not the same object, and no arrangement of digits changes that.
The pattern tells you how scarce the number is. The grade tells you what the note is worth. We can give you the first exactly, because it is arithmetic on a closed set. Nobody can give you the second from eight digits.
A star at the end is a different question
If your serial ends with a ★ instead of a letter, the note is a replacement — printed to stand in for one spoiled during production. That has nothing to do with the digits and everything to do with how many notes were printed alongside it, which the Bureau of Engraving and Printing publishes. Some replacement runs are enormous; a few are in the low thousands. Look up the print run.
A note can be both, and that is the combination collectors actually chase: a short-run star note whose serial also makes a pattern. If you are not sure which of the two you are holding, start at the serial number lookup — it runs both checks on the same number.
Where the odds come from
The universe is the eight-digit range 00000001 to 99999999: 99,999,999 serial numbers, because 00000000 is never printed. Every count in the table above was produced twice, on purpose and by different means — once by testing all 99,999,999 serials one at a time against the same code that runs in the tool above, and once by deriving each figure by hand from combinatorics. The two agree. The check is re-run automatically every time the tool changes, so the table and the tool cannot drift apart.
Taken together the twelve patterns cover a little over 1.7% of the range, which is the number behind the answer most people get: about 98 notes in every 100 have a serial with no pattern at all. That is not a disappointing result, it is the ordinary one — and a serial with nothing in it takes nothing away from a note whose series, condition or star make it interesting.
The tool can also keep a list of the serials you have checked, in your own browser. There is no account and we never see it.