Something which has the same value or amount (as something else). (attributive use passing into adjective, below)
To amount to as much; to be equivalent.
being essentially equal to something
"it was as good as gold"
"a wish that was equivalent to a command"
"his statement was tantamount to an admission of guilt"
Equivalent in meaning or effect; amounting to the same thing in practical terms, even if being technically distinct.