Transactions on the Terracoin network are recorded in blocks on the blockchain. The size of each transaction is measured in bytes, but there is not necessarily a correlation between high value transactions and the number of bytes required to process the transaction. Instead, transaction size is affected by how many input and output addresses are involved, since more data must be written in the block to store this information. Each new block is generated by a miner, who is paid for completing the work to generate the block with a block reward. In order to prevent the network from being filled with spam transactions, the size of each block is artificially limited. As transaction volume increases, the space in each block becomes a scarce commodity. Because miners are not obliged to include any transaction in the blocks they produce, once blocks are full, a voluntary transaction fee can be included as an incentive to the miner to process the transaction. Most wallets include a small fee by default, although many miners will process transactions even if no fee is included.
The release of Terracoin 0.12.2.1 and activation of DIP0001 saw a simultaneous reduction of fees by a factor of 10, while the block size was increased from 1MB to 2MB to promote continued growth of low-cost transactions even as the cost of Terracoin rises. Terracoin also supports InstantSend and PrivateSend transactions, which operate on a different and mandatory fee schedule. The fee schedule as of December 2017 is as follows:
|Transaction type||Recommended fee||Per unit|
|Standard transaction||.00001 TRC||Per kB of transaction data|
|InstantSend||.0001 TRC||Per transaction input|
|PrivateSend||.001 TRC||Per 10 rounds of mixing (average)|
Terracoin 0.12.1.5 recommended fee schedule as of December 2017
As an example, a standard and relatively simple transaction on the Terracoin network with one input, one output and a possible change address typically fits in the range of 200 - 400 bytes. Assuming a price of $0.80 USD per TRC, the fee falls in the range of $0.0000015 - $0.0000030, or well under half a cent. Processing the transaction using InstantSend at the same price would add $0.00008 to the transaction. These fees apply regardless of the TRC or dollar value of the transaction itself.
PrivateSend works by creating denominations of 10, 1, 0.1 and 0.01 TRC and then mixing these denominations with other users. Creation of the denominations is charged at the default fee for a standard transaction. Mixing is free, but to prevent spam attacks, an average of one in ten mixing transactions are charged a fee of 0.001 TRC. Spending inputs mixed using PrivateSend incurs the usual standard or InstantSend fees, but to avoid creating a potentially identifiable change address, the fee is always rounded up to the lowest possible denomination. This is typically .01 TRC, so it is important to deduct the fee from the amount being sent if possible to minimise fees. Combining InstantSend and PrivateSend may be expensive due to this requirement and the fact that a PrivateSend transaction may require several inputs, while InstantSend charges a fee of 0.0001 TRC per input. Always check your fees before sending a transaction.