Some blockchains use variable fee structures that depend on network activity. On these blockchains, fees can be high due to network congestion. The fee amount you pay for a transaction determines its priority. The higher the fee, the faster the transaction gets confirmed.

Fireblocks allows you to set the fee when you create a new transaction. Learn more in the adjusting network transaction fees article. However, the fee amounts you set are only estimates and the amount you will actually pay when the transaction gets confirmed may be different.

The actual amount you pay is only determined after the transaction is sent to the blockchain since network fee rates change rapidly and may differ by the time the transaction is confirmed.

Viewing actually spent transaction fees

You can view the actual fees you paid in your Fireblocks Console’s Transaction History page, through a Fireblocks API endpoint, or by setting up a Webhook notification event.

• Transaction history: Expand the transaction details. The fee value shows under Network Fee.
• API endpoints: GET - api.fireblocks.io/v1/transactions/external_tx_id/{externalTxId}/ 
• Webhook event: "TRANSACTION_STATUS_UPDATED"

You can only see a transaction’s actual fee when its transaction status is confirming or completed. When you retrieve existing transactions via Fireblocks API, any transactions that have statuses besides the two above may show -1 in the fee field, meaning the fee is not yet known.