## Bitcoin transaction priority calculation

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From the Bitcoin wiki page on transaction fees:

Transaction priority is calculated as a value-weighted sum of input age, divided by transaction size in bytes:

priority = sum(input_value_in_base_units * input_age)/size_in_bytes Transactions need to have a priority above 57,600,000 to avoid the enforced limit

Can somebody clarify what input_value_in_base_units or input_age is?

input_value_in_base_units is the number of satoshis that the input is worth. One Bitcoin is worth 100,000,000 satoshis.
input_age is how many blocks the input has been present for. An unconfirmed transaction has an age of 0, and one that has 100 confirmations has an age of 100.