A Monero primary address: exactly ninety five characters, opening with the digit 4, in an unbroken run.
The shape
- Total width
- 95 characters, fixed, with no permitted variation
- First character
4- Alphabet
- base58 as used on this chain, with the same four omissions listed at the alphabets
- Case
- mixed, and both cases carry meaning
- Internal structure
- not visible; the string is one run with no fields a reader can pick out
- Tail
- a checksum derived from everything in front of it
4EXAMPLEEXAMPLEEXAMPLEEXAMPLEEXAMPLEEXAMPLEEXAMP\
LEEXAMPLEEXAMPLEEXAMPLEEXAMPLEEXAMPLEEXAMPLExxx\ marks the break and is not part of the string. A real address has no line breaks in it.The alphabet is the base58 used by the older Bitcoin form, so the same four lookalike characters are missing from it and the same reading habits carry across. What does not carry across is the width. A reader used to thirty character addresses will find this one uncomfortably long, and the length is what does most of the work on this card.
Ninety five characters is long enough that it will wrap in almost any narrow column, and wrapping is where most of the damage to this shape happens. A wrapped string looks like two strings. Selecting one visual line and not the other produces a short string that is obviously wrong once counted and not obviously wrong at a glance.
How to check it by eye
Counting to ninety five
- Read the first character. It is
4. If it is8you are holding a different kind, covered on the subaddress card. - Count in tens using the grouping method on counting by eye. You are looking for nine full groups and a remainder of five.
- Hold the string against a Bitcoin address for width. If it is anywhere near that short, the count is not going to reach ninety five and you can stop.
- Look for a space or a line break inside the run. Neither belongs, and a wrapped copy often brings one along.
What a wrong shape means
Ninety four or ninety six characters is the signature of a clumsy selection. One short means the drag stopped a character early; one long means it picked up a punctuation mark, a bracket or a full stop that belonged to the sentence around the string.
One hundred and six characters is not a damaged address. It is a different kind of address, and it is described on the next card in this family. A string opening with 8 is likewise a different kind rather than a fault.
A width that is nowhere near ninety five, with the alphabet still clean, generally means the string belongs to another chain. Widths in the twenties and thirties belong to the Bitcoin forms; sixty four hexadecimal characters is an identifier rather than an address.
A run that measures ninety five characters and still contains one of the four excluded characters is a different sort of fault. The width survived and the alphabet did not, which points at transcription rather than selection: machines copy whole strings or short ones, while people substitute characters.
None of these outcomes identifies a culprit. They identify a copying step, a rendering step or a chain mismatch, which is where a reader should look first.
Why the count carries weight here
Most shapes on this reference permit a range of widths, so counting characters produces a soft answer: the string is plausible, or it is not. This one permits a single width. That turns the count from a sanity check into a real test, since any string that is not ninety five characters long is not this shape, whatever else is true of it.
The strictness cuts both ways, and the second direction is the useful one. Truncation is the most common accident that befalls a long string, and truncation always shortens. A fixed width means every truncation is detectable by a reader with no tools, working from the string alone, in about the time it takes to read this sentence. Very few checks on this site are that clean.
What the count cannot do is survive being done carelessly. Counting to ninety five by eye is error prone at the boundaries, which is why grouping in tens matters and why a recount is worth the trouble when the first count lands at ninety four or ninety six.
What a correct shape does not prove
Ninety five clean characters opening with 4 is a well formed primary address. Beyond that, the string is silent on all of the following.
- Whose wallet it belongs to. No part of the run encodes a person, a handle or a role.
- Whether it is the address you were sent, rather than a different well formed address that arrived in its place.
- Whether your count was accurate. A miscount in either direction produces a false result in both directions.
- Whether the address has ever been used, or is still in use. This site queries no chain and prints no history.
- Whether the string on your screen is the string that will be used, if any part of the journey involved retyping.
What this card is not
Subaddresses and integrated addresses share most of this shape and are separated from it on the next card. The identifier that appears after a payment is a transaction id, which looks nothing like this. The quantity being sent is an amount and its decimal places, and the alphabet itself is on the alphabets.