The PAN (primary account number) is the 16-digit number that identifies a payment card account. It is usually printed on the front of the card in four groups of four digits, though sometimes the number is printed on the back. The PAN is globally unique: every payment card in the world has a different number. With 16 digits, each ranging from 0–9, the raw number of possible combinations is 10,000,000,000,000,000 or ten quadrillion. However, not all combinations are valid PANs, because of how the numbers are allocated and calculated.
## PAN format
The PAN format is controlled by ISO/IEC 7812, and the American Bankers Association is the registration authority. PANs are constructed according to this schema.
|1–6||BIN (bank identification number), obtained from your sponsor bank. Visa is currently not offering 6-digit BINs but only 8-digit BINs.|
|7–8||Standard range. These ranges are provided by the sponsor bank and have become standard in the last few years. As 6-digit BINs become more scarce, networks have mandated their use. A standard implementation gets 10 ranges, such as 00–09 or 30–39.|
|9||An optional range that will become more popular in the next few years. The 9-digit range is common with mobile wallet ranges. Galileo does not currently support 9-digit BINs.|
|9–15<br>10–15||Randomized digits for the individual account number. If position 9 is not used as a range digit, it is part of the randomized digits.|
|16||Check digit, calculated by the Luhn algorithm. If one or more of the other digits is changed, this check digit becomes invalid, so PAN validators can reject an altered PAN right away.|
## Number usage
When allocating PANs for individual accounts, Galileo uses randomization to assign the individual account numbers. This security measure makes it harder for fraudsters to guess which PANs are valid: if they increment a valid account number by 1, it is less likely to also be a valid number than if the numbers were assigned sequentially.
The more PANs Galileo assigns, the harder it becomes for Galileo to find a unique number to use. At around 70–80% of the range's capacity, it becomes too time-consuming to find a unique number, so a new BIN must be used.
Assuming that Galileo uses 75% of available numbers, here are the numbers of PANs that you can use.
|BIN digits + ranges||Available account numbers||Example range|
|6 + 1 range||7,500,000||5555 5500 0000 000x – <br>5555 5500 9999 999x|
|6 + 10 ranges||75,000,000||5555 5500 0000 000x – <br>5555 5509 9999 999x|
|6 + 100 ranges||750,000,000||5555 5500 0000 000x – <br>5555 5599 9999 999x|
If the bank gives you one range, your PANs all begin with 5555 5500, which provides 7.5 million PANs.
On the other hand, If the bank assigns you a BIN of 5555 55 and provides 10 ranges, the BINs for your cards would go from 5555 5500 to 5555 5509. With an average of 75% usage, you would have 75 million PANs at your disposal.
In extraordinary cases, a card program could get 100 ranges (the maximum possible with the first 8 digits), so the BINs would range from 5555 5500 through 5555 5599, which would yield 750 million PANs.