There are different internal metrics that could be used, ranging from
variable mining difficulty through to transaction fees.
Some chains, like Bitcoin Cash for example, have
variable mining difficulties that change based on the amount of throughput transactions being processed on the chain.
Not exact matches
When calculating the cost of
mining, the following are considered: - Cost of equipment, cost of electricity and other
variables such as the hash rate,
difficulty, Bitcoins per block and the fees associated with
mining in a pool, etc..