See also: target Contents 1 2 3 4 5 6 7 8 9 Difficulty is a measure of how difficult it is to find a hash below a given target.The Bitcoin network has a global block difficulty.Valid blocks must have a hash below this target.Mining pools also have a pool-specific share difficulty setting a lower limit for shares.difficulty = difficulty_1_target / current_target (target is a 256 bit number) difficulty_1_target can be different for various ways to measure difficulty.Traditionally, it represents a hash where the leading 32 bits are zero and the rest are one (this is known as "pool difficulty" or "pdiff").The Bitcoin protocol represents targets as a custom floating point type with limited precision; as a result, Bitcoin clients often approximate difficulty based on this (this is known as "bdiff").Each block stores a packed representation (called "Bits") for its actual hexadecimal target.The target can be derived from it via a predefined formula.

For example, if the packed target in the block is 0x1b0404cb, the hexadecimal target is Note that the 0x0404cb value is a signed value in this format.The largest legal value for this field is 0x7fffff.To make a larger value you must shift it down one full byte.Also 0x008000 is the smallest positive valid value.The highest possible target (difficulty 1) is defined as 0x1d00ffff, which gives us a hex target of It should be noted that pooled mining often uses non-truncated targets, which puts "pool difficulty 1" at So the difficulty at 0x1b0404cb is therefore: And: Here's a fast way to calculate bitcoin difficulty.It uses a modified Taylor series for the logarithm (you can see tutorials on flipcode and wikipedia) and relies on logs to transform the difficulty calculation: To see the math to go from the normal difficulty calculations (which require large big ints bigger than the space in any normal integer) to the calculation above, here's some python: Current difficulty, as output by Bitcoin's getDifficulty.

Graphs There is no minimum target.ethereum myrThe maximum difficulty is roughly: maximum_target / 1 (since 0 would result in infinity), which is a ridiculously huge number (about 2^224).offizielle bitcoin appThe actual maximum difficulty is when current_target=0, but we would not be able to calculate the difficulty if that happened.litecoin single mining(fortunately it never will, so we're ok.)dogecoin gbpSee discussion in target.bitcoin cairoThe minimum difficulty, when the target is at the maximum allowed value, is 1.ethereum ipo

The difficulty is adjusted every 2016 blocks based on the time it took to find the previous 2016 blocks.At the desired rate of one block each 10 minutes, 2016 blocks would take exactly two weeks to find.If the previous 2016 blocks took more than two weeks to find, the difficulty is reduced.If they took less than two weeks, the difficulty is increased.The change in difficulty is in proportion to the amount of time over or under two weeks the previous 2016 blocks took to find.To find a block, the hash must be less than the target.The hash is effectively a random number between 0 and 2**256-1.The offset for difficulty 1 is and for difficulty D is The expected number of hashes we need to calculate to find a block with difficulty D is therefore or just The difficulty is set such that the previous 2016 blocks would have been found at the rate of one every 10 minutes, so we were calculating (D * 2**48 / 0xffff) hashes in 600 seconds.That means the hash rate of the network was over the previous 2016 blocks.

Can be further simplified to without much loss of accuracy.At difficulty 1, that is around 7 Mhashes per second.At the time of writing, the difficulty is 22012.4941572, which means that over the previous set of 2016 blocks found the average network hash rate was (The eternal question.)The average time to find a block can be approximated by calculating: where difficulty is the current difficulty, hashrate is the number of hashes your miner calculates per second, and time is the average in seconds between the blocks you find.For example, using Python we calculate the average time to generate a block using a 1Ghash/s mining rig when the difficulty is 20000: and find that it takes just under 24 hours on average.Any one grinding of the hash stands the same chance of "winning" as any other.The numbers game is how many attempts your hardware can make per second.You need to know the difficulty (above) and your khash/sec rate (reported by the client).Mining Hardware Comparison has some stats that may help you predict what you could get.

Visit a calculator or perform the maths yourself, /bitcoin/calculator.php /bitcoincalculator.php /calculator /bitcoin-mining-calculator Remember it's just probability!There are no guarantees you will win every N days.Bitcoin Difficulty History What is Bitcoin Mining Difficulty?_ Here's how it works: Anybody can ask a question Anybody can answer The best answers are voted up and rise to the top up vote 4 down vote favorite 1 I'm new to bitcoin; please bear with me.I'm looking into mining, how it works, and how to get started.I see a "mining difficulty" from many sources and list a 3 billion something number without units.What exactly does this number mean and how does it relate to the processing speed of the hardware used?For example, what predictions can be made on the number blocks you will solve with a 100 Gh/s ASIC at any given difficulty?I assume Gh/s is giga hashes per second, though I don't know what a hash is either.

I found this related question, but I don't understand the answer.As an extension question, how might this relate to mining in a pool?Bitminter says it has 424 Th/s, so my 100 Gh/s is a drop in the bucket.difficulty hash hashpower up vote 4 down vote (If I may repeat myself a bit...)Mining is like having a lot of people throwing weighted coins (such that 1 millionth of the time it comes up heads) and telling you when they hit a heads.If one such "heads" is reported every 10 minutes (600 seconds), you can make a very accurate estimation of how many times per second the coins are being flipped.In this example: (1,000,000 flips/heads) / (600 seconds/heads) ~= 1,667 flips/second The network difficulty is how you adjust this 1,000,000 figure so that the 600 figure stays consistent as the network's total hash power (1,667) changes.To see real-world calculations of how the difficulty affects the coins discovered per time spent, see any mining profitability calculator, and change the "difficulty" figure.

The Bitcoin wiki has details on difficulty, as well.I don't know what a hash is either.When mining, your computer creates a block of data, which has a list of all of the transactions it knows about, includes a transaction that pays you the mining bonus, and then hashes that.If the hash happens to be a small enough number (as defined by the difficulty), the block is valid.If it's not, you increment a random number called a "nonce" that's in the block, so that the block has the same meaning but different data, and hashes the block again.(the nonce is included from the start, of course, but I didn't mention it to avoid being confusing) The details of the block hash are explained in more detail at Bitcoin wiki's Block hashing algorithm.Gigahashes per second, then, are how many billion times your hardware can do this hash per second.If the pool you're in has 424 Th/s and you have 100 Gh/s, then you are about 1/4000th of your pool's total power.You can expect to be the one to solve about 1/4000th of the blocks (on average) that your pool finds.

(technical details intentionally omitted; those are available at my various links, and your link) up vote 3 down vote Miners task is to find a hash below a target T. Obviously if T is smaller, its more difficult to find the hash number.Difficulty D is defined by: D = Tmax/T where Tmax is: 2^224 The probability of finding the hash is: P = T/2^256 which is equal to 1/D2^32 So if you can make h number of hashes in t time, the probability of finding the target hash is: P = ht/D2^32 up vote 1 down vote I'm looking into mining, how it works, and how to get started.The difficulty is just an arbitrary value, it has no unit.A difficulty 8 block is 8 times more difficult than a difficulty.Today the difficulty is 3B, but this chances on a bi-weekly basis as the hashrate of the network varies.It takes about 4 Billion attempts to find a difficulty 1 block, you can scale up approximately from here.100 GH means the hardware makes 100,000,000,000 attempts a second, or about a difficulty 1 block every 0.04 seconds.