Where the ninety five characters come from
The address packs a network byte, two public keys and a checksum, and the whole thing is written in base58, an alphabet picked to leave out characters that look like each other. That payload encodes to ninety five characters for a standard address, every time, with no short form and no long form.
The first character is not decoration. It is what the leading network byte encodes to. A standard address on the main network begins with 4 and a subaddress begins with 8. An integrated address, which carries a payment identifier inside itself, runs to a hundred and six characters instead.
None of this is market specific. It is how the coin writes addresses, so every address you are ever handed by anyone follows the same layout.
| Kind | Characters | First character |
|---|---|---|
| Standard address | 95 | 4 |
| Subaddress | 95 | 8 |
| Integrated address | 106 | 4 |
The check ninety five characters allows
Count, then look at the front. If the count is neither ninety five nor a hundred and six, or the first character is neither 4 nor 8, stop there. It is the same cheap triage as the count on the fifty six character page, applied to the other kind of long string in this subject.
What it catches most often is truncation. Chat clients wrap long strings, forums insert breaks, screenshots cut at the edge of the frame. A short address is a damaged address, and it will fail rather than send coin somewhere unintended, which is a small mercy.
The check earns its ten seconds because of the zero at the start of this section. There is no step after the send. Counting is the last cheap thing available to you, and a seed is a different string again, covered on the twenty five word page.
Ninety five characters mistaken for something else
The commonest confusion is between a payment address and a mars market address. Both are long runs of characters nobody reads, and they have nothing to do with each other. One names a destination for coin. The other names a service on the network. Sending coin to an onion hostname is not a thing that can happen, and pasting a payment address into a browser opens nothing.
The second is assuming the leading character is style. It is the network byte showing through, so a 4 and an 8 are telling you which kind of address you are holding, and a string starting with anything else on the main network is not an address for this coin at all.
The third is treating a correct length as approval. Every hostile address is exactly the right length, because whoever produced it used the same software as everybody else. Length and first character rule out damage and clumsy fabrication. They say nothing whatever about who is at the other end.
What changes which length you see
Only which kind of address you were given. A vendor or a market using subaddresses hands out a fresh string starting with 8 for each payment, which is ordinary practice and lets the receiver tell payments apart without an identifier attached to them.
Integrated addresses do that same job the older way, with the identifier packed into the string, which is where the extra eleven characters go. They turn up less often now than they used to.
What never changes is the arithmetic underneath. Amounts, addresses and keys are all fixed length structures, and the numbers in this section describe them rather than any market that happens to use them. The decimal page is the other half of that picture.
Questions people ask
Why does the address I was given start with 8?
It is a subaddress, the same length as a standard address and generated fresh for each payment. Nothing about it is unusual.
Is a payment address the same as a mars market address?
No. One is an onion hostname naming a service and the other is a destination for coin. They use different alphabets, different lengths and different software.
Does the right length mean the address is genuine?
No. Every address produced by ordinary wallet software is the right length, including one belonging to somebody you never meant to pay.