Bitcoin difficulty changes every day in every possible way

There is no master document at all. Instead, the ledger is broken up into blocks: Every block includes a reference to the block that came before it, and you can follow the links backward from the most recent block to the very first block, when bitcoin creator Satoshi Nakamoto conjured the first bitcoins into existence. Every 10 minutes miners add a new block, growing the chain like an expanding pearl necklace. Generally speaking, every bitcoin miner has a copy of the entire block chain on her computer.

If she shuts her computer down and stops mining for a while, when she starts back up, her machine will send a message to other miners requesting the blocks that were created in her absence. No one person or computer has responsibility for these block chain updates; no miner has special status. The updates, like the authentication of new blocks, are provided by the network of bitcoin miners at large. Bitcoin also relies on cryptography.

The computational problem is different for every block in the chain, and it involves a particular kind of algorithm called a hash function. Like any function, a cryptographic hash function takes an input—a string of numbers and letters—and produces an output. But there are three things that set cryptographic hash functions apart:. The hash function that bitcoin relies on—called SHA, and developed by the US National Security Agency—always produces a string that is 64 characters long.

You could run your name through that hash function, or the entire King James Bible. Think of it like mixing paint. If you substitute light pink paint for regular pink paint in the example above, the result is still going to be pretty much the same purple , just a little lighter.

But with hashes, a slight variation in the input results in a completely different output:. The proof-of-work problem that miners have to solve involves taking a hash of the contents of the block that they are working on—all of the transactions, some meta-data like a timestamp , and the reference to the previous block—plus a random number called a nonce.

Their goal is to find a hash that has at least a certain number of leading zeroes. That constraint is what makes the problem more or less difficult. More leading zeroes means fewer possible solutions, and more time required to solve the problem. Every 2, blocks roughly two weeks , that difficulty is reset. If it took miners less than 10 minutes on average to solve those 2, blocks, then the difficulty is automatically increased. If it took longer, then the difficulty is decreased.

Miners search for an acceptable hash by choosing a nonce, running the hash function, and checking. When a miner is finally lucky enough to find a nonce that works, and wins the block, that nonce gets appended to the end of the block, along with the resulting hash.

Her first step would be to go in and change the record for that transaction. Then, because she had modified the block, she would have to solve a new proof-of-work problem—find a new nonce—and do all of that computational work, all over again.

Again, due to the unpredictable nature of hash functions, making the slightest change to the original block means starting the proof of work from scratch. What we're suggesting is that the rate Bitcoin difficulty is increasing is not fixed, and can be anticipated.

Right now, in December , Bitcoin is very popular, with thousands of new investors and miners every day - so significant difficulty increases are to be expected. Many new people are interested in bitcoin mining, allowing hardware manufacturers to sell miners in larger quantities, causing more total hashpower to be available - driving Bitcoin difficulty up. The key relationship here is that the amount of new hardware becoming available is strongly linked to the demand for it.

A risk is that if the people making these miners produce too many, the difficulty will rise so fast that Bitcoin mining profitability goes down massively. This occurred for Dash when the Antminer D3 came out. There are also scenarios that can cause Bitcoin's difficulty to decrease. August is a good example of this, where a lot of miners moved their hashpower to mine Bitcoin Cash as it was more profitable at the time.

This decreased hashpower mining Bitcoin, causing Bitcoin's difficulty to decrease for 2 weeks. If you stay up-to-date with these types of scenarios and mine the more profitable coins Bitcoin Cash in this scenario , you can get extra coins for 2 weeks and sell them immediately for a great return on investment or just HODL them! Another argument suggesting Bitcoin mining will remain profitable long-term is to look at it from the perspective of large mining operations.

If you were a miner running a large setup, and Bitcoin mining was to no longer be profitable, then you'd likely start mining something else that was. If there were no profitable coins for a long period of time, you'd likely have very high operating costs and be forced to shut down your operation eventually.

For a smaller miner running just a few Antminers or some cloud mining, this would be less of an issue. So in theory as long as Bitcoin stays popular and its price continues to increase, if you can get cheap electricity Bitcoin mining should always stay profitable. This last argument in particular is very speculative, so be aware that for a worst-case scenario if Bitcoin's price was to fall for a long-period of time, even if you had cheap electricity, there's a risk that mining it would no longer be profitable.

In June , the reward for Bitcoin mining will half. This could cause big issues in the long-term as it essentially makes it half as profitable overnight. We've posted a video explaining the cause of this here. Looking at the Blockchain chart above for the past 2 years, it definitely looks exponential; e.

But the figures for the past 3 years don't do that, they vary significantly. In it took around 11 months for the difficulty to double, in early around 6 months, in late around 8 months and then in between months.

Rather than doubling at a consistent interval, it seems to vary based on factors like available hardware and public interest. What we're suggesting is that the rate Bitcoin difficulty is increasing is not fixed, and can be anticipated. Right now, in December , Bitcoin is very popular, with thousands of new investors and miners every day - so significant difficulty increases are to be expected.

Many new people are interested in bitcoin mining, allowing hardware manufacturers to sell miners in larger quantities, causing more total hashpower to be available - driving Bitcoin difficulty up. The key relationship here is that the amount of new hardware becoming available is strongly linked to the demand for it. A risk is that if the people making these miners produce too many, the difficulty will rise so fast that Bitcoin mining profitability goes down massively.

This occurred for Dash when the Antminer D3 came out. There are also scenarios that can cause Bitcoin's difficulty to decrease.

August is a good example of this, where a lot of miners moved their hashpower to mine Bitcoin Cash as it was more profitable at the time. This decreased hashpower mining Bitcoin, causing Bitcoin's difficulty to decrease for 2 weeks. If you stay up-to-date with these types of scenarios and mine the more profitable coins Bitcoin Cash in this scenario , you can get extra coins for 2 weeks and sell them immediately for a great return on investment or just HODL them!

Another argument suggesting Bitcoin mining will remain profitable long-term is to look at it from the perspective of large mining operations. If you were a miner running a large setup, and Bitcoin mining was to no longer be profitable, then you'd likely start mining something else that was. If there were no profitable coins for a long period of time, you'd likely have very high operating costs and be forced to shut down your operation eventually.