The early days of Bitcoin mining are often described as a gold rush.
Satoshi Nakomoto’s invention of Bitcoin, “a peer-to-peer electronic cash system,” opened up an entirely new frontier, not just of freedom but of occasionally outrageous profits.
Those with a strong interest in such things, namely cypherpunks, cryptographers, technically-minded libertarians and assorted hackers, were first to stake their claim.
But is there still gold in them thar hills?
The fact is:
Bitcoin mining has grown from a handful of early enthusiasts into a cottage industry, into a specialized industrial-level venture. The easy money was scooped out a long time ago and what remains is buried under the cryptographic equivalent of tons of hard rock.
The sad truth is:
Only those with specialised, high-powered machinery are able to profitably extract bitcoins nowadays. While mining is still technically possible for anyone, those with underpowered setups will find more money is spent on electricity than is generated through mining.
In other words, mining won’t be profitable at a small scale unless you have access to free or really cheap electriciy.
We’ll explain this situation in depth but first, you need to know a few basic technical terms from the world of Bitcoin mining:
A group of Bitcoin transactions, chosen from the mempool (the list of all currently pending transactions) and recorded by a miner into the ever-growing record of blocks known as “the blockchain.”
A new block is created on average every ten minutes.
This is the cryptographic work which miners perform in order to find the solution which allows them to define a new block.
PoW hashing ensures the proper function of the Bitcoin blockchain. Miners compete to solve a cryptographic “puzzle,” known as a hash.
There are no shortcuts in this process, which can only be solved with raw computational power.
By correctly hashing the current block, miners prove their investment of work and are rewarded with a certain number of newly-created bitcoins.
The number of newly-created bitcoins, awarded to whichever miner creates a block.
This number was initially set to 50, halved to 25 in late-2012, and halved again to 12.5 in mid-2016. The next halving event expected is around mid-2020.
This halving process will continue in this fashion, halving the block reward approximately every four years / 210,000 blocks, until all 21 million bitcoins are created.
Achieving the block reward is the only valid way in which new bitcoins can be created; by miners according to the code’s rate and limit.
Hashrate is the measure of a miner’s computational power.
The higher their relative power, the more solutions (and hence, block rewards) a miner is likely to find.
Initially measured in hash per second (H/s), due to the increasing speed of mining hardware. H/s was soon commonly pre-fixed with SI units as follows:
In early 2017, Bitcoin’s collective hashrate reached nearly 4 Exahash. This represents a tremendous investment into mining hardware, the R&D of such hardware, and electrical expenditure.
With hashrate shooting up over the years, it would seem blocks would be found by miners ever more rapidly.
Bitcoin’s Difficulty measure is what prevents this from happening. It adjusts to hashrate to ensure that blocks are found roughly every 10 minutes.
Note how closely Difficulty matches Hashrate in the 2 charts above.
When total hashrate rises, the Difficulty of POW hashing adjusts upwards – and the inverse also applies.
Difficulty auto-adjusts every two weeks (or 2016 blocks).
Watts per hashrate per second. Electricity is the major on-going cost of Bitcoin mining. The price paid per Watt will greatly influence profitability.
Unless you command a tremendous hashrate, your odds of solving a block by yourself (i.e. “solo-mining”) are extremely low.
By banding together with other miners in a so-called pool, your combined odds of solving a block rise proportional to the pool’s total hashrate.
Whenever they solve blocks, pools reward individual miners according to their contributed hashrate (minus commissions and the like).
With these terms in mind, it’s possible to calculate the current profitability (circa March 2017) of Bitcoin mining for your circumstances.
The future profitability of mining cannot be reliably predicted.
This is due to the ever-changing nature of the Difficulty modifier and the BTC price, in particular.
To begin, we must select a suitable ASIC mining rig. To aid in selection, the Bitcoin Wiki provides a handy mining hardware comparison :
Although Bitcoin Wiki doesn’t list many models as currently shipping on from their manufacturers, all these mining rigs (and more) are available for resale as new or used.
The AntMiner S9 is a modern mining rig which offers a good hashrate for its power consumption.
It’s pretty much the cutting edge of mining tech so we’ll select it for our example.
The S9 is available for roughly $1800 up to $2400 from Amazon, or about $1365 from BitMain, shipping excluded. Power supply units will add another $120 or so to the price.
Next, we need to enter the S9’s specs and cost, as well as other info such as power cost and pool fees, into a suitable number-cruncher.
CoinWarz.com offers a good mining profitability calculator, which automatically fills in the current BTC price, Difficulty and block reward info. Note that the Hardware Costs field does not seem to influence the final calculation.
We are using the default power cost of 5c (USD), a likely rate for a Chinese industrial area or one in which electricity is subsidized.
To determine your own power cost, check worldwide electricity prices or your utility bill for the exact price.
The 0% Pool Fee assumes a mining farm large enough to run its own pool. Smaller pools will generally offer lower or even no fees, but keep in mind they will seldom find blocks.
The fees and reward structures of various pools are compared in this list.
Once all the necessary info is entered, hit Calculate for the profitability result:
An excellent result! At this rate, the S9 unit would pay for itself within a year as well as make about $600 in profit! As a large miner would be able to negotiate a lower unit price on each S9, we can assume they’ll research profit even sooner.
Before getting too excited about your potential mining profits, let’s recalculate them using the average residential Power cost per kWh in the USA (~12.5c) and a typical pool fee of 1%.
It’s not looking so great now.
At a Bitcoin price around $1150, it appears that the average American home miner makes only $1348 a year, assuming difficulty and price hold steady. In other words, the unit will pay for itself within a year.
This is a dangerous assumption! Bitcoin’s total hashrate – and thus its difficulty, has been consistently rising since the early years, sometimes jumping by double digit percentages within a month!
Therefore, any calculations should be regarded skeptically, as likely best-case scenarios.
Sources of Unexpected Profit Loss:
Occasionally, Bitcoin hashrate spikes as a big new mining pool comes online. This happened in early 2016:
It’s quite possible that even some big, corporate miners found their profit margins under threat from the resulting steep spike in competition. Indeed, in mid-2016, Swedish Bitcoin mining firm KnCMiner declared bankruptcy.
The home miner really has no chance to compete in such a challenging environment, unless they have access to free or extremely low-cost electricity…
Also bear in mind that the rate of obsolescence in Bitcoin mining hardware is quite fast! New, more efficient mining hardware may be released at any time, although we are reaching the technological limits of improved efficiencies.
If (pre-)ordering any such equipment, be aware that potential manufacturing, shipping, customs or other delays could end up being very costly as difficulty rises or price falls during the interim.
There are plenty of other things which can wrong, for example:
Such downside risks must always be factored into any sound business plan.
The average home miner will struggle to be profitable or recoup the cost of mining hardware and electricity.
Profitability is highly unlikely given the current circumstances.
The situation may improve in future once ASIC mining hardware innovation reaches the point of diminishing returns.
That, coupled with cheap, hopefully sustainable power solutions may once again make Bitcoin mining profitable to small individual miners around the world.
This would also greatly improve the decentralization of the Bitcoin network, hardening it against legislative risk.