How Many Confirmations Are Generally Considered Secure for a Bitcoin Transaction?

While a single confirmation means the transaction has been included in the latest block, the generally accepted standard for a secure, irreversible transaction is six confirmations. This means six subsequent blocks have been mined and linked to the block containing the transaction.

With six confirmations, the computational cost required to reverse the transaction via a chain reorganization is considered astronomically high, making a double-spend attempt economically infeasible.