What is Bitcoin mining difficulty?
Definition · Mining difficulty
A number that says how hard it is to find a block hash below the network’s target, compared with the easiest target Bitcoin allows. Difficulty 2 is twice as hard as difficulty 1. The network recalculates it every 2,016 blocks.
Miners hash a block header over and over, changing a small field each time, until the result comes out below a number called the target. There’s no shortcut. It’s pure guessing, and the only way to guess faster is more hardware.
Difficulty is the dial that sets how low that target is. Nobody turns it by hand. Every node runs the same arithmetic on the same block timestamps and gets the same answer.
132.8 trillion
Current difficulty
latest block, live
950 EH/s
Hashrate it implies
difficulty × 2³² ÷ 600
2,016
Blocks per period
consensus rule
10 min
Target block time
14 days per period
What is the target, and why the leading zeros?
A block hash is a 256-bit number, usually written as 64 hex digits. The target is a number of the same size, and a valid block needs a hash at or below it. A lower target means more zeros at the front, which means fewer hashes qualify.
A block hash has to be below this number
Difficulty 1
8 leading zeros
The easiest target the rules allow. The first blocks in 2009 used it.
00000000ffff0000000000000000000000000000000000000000000000000000
Today: difficulty 132.8 trillion
19 leading zeros
Worked out from the live difficulty, refreshed every 10 minutes.
000000000000000000021ec50000000014150d707576190b7fc44ceb4d6b138b
The formula ties the two together: difficulty = target at difficulty 1 ÷ current target. A miner needs about difficulty × 2³² hashes, on average, to find one block. You can feel the “one more zero is 16 times harder” rule yourself below, with a tiny block your browser mines.
Interactive · mine a block in your browser
Real SHA-256d proof of work, simplified header
Block hash (double SHA-256)
Edit the transactions: the hash changes completely with a single letter.
Attempts: 0
Your hashrate: n/a
Time: 0.0 s
How does the difficulty adjustment work?
At every block height divisible by 2,016, each node looks at how long the last period took and rescales difficulty so the next one would take 14 days at the same hashrate.
How much difficulty changes, by how long the last 2,016 blocks took
Blocks came too fast? The period took less than 14 days, so difficulty goes up. Too slow? It goes down. The cap stops a sudden swing, for example after a big outage, from wrecking the next period.
| Period took | Block time | Change |
|---|---|---|
| 12 days | 8.6 min | +16.7% |
| 13 days | 9.3 min | +7.7% |
| 14 days | 10.0 min | 0% |
| 15 days | 10.7 min | −6.7% |
| 3 days | 2.1 min | +300% (×4 cap) |
When is the next difficulty adjustment?
The next adjustment is expected around , at block 969,696. The current estimate is −2.05%, based on an average block time of 10.21 minutes so far this period.
−2.05%
Estimated change
live estimate
57.4%
Period done
858 blocks left
Estimated date
UTC
+4.16%
Last adjustment
for comparison
Treat the estimate as a moving target. Early in a period it rests on few blocks, so it swings. It settles as the period fills. The dial at the top of the page updates every 10 minutes.
How is difficulty related to hashrate?
Closely. To find one block every 600 seconds at a given difficulty, the whole network has to hash at about this rate:
Network hashrate, read two ways (live)
That’s also how public hashrate figures are made. Nobody can count every machine, so hashrate is estimated from difficulty and how quickly recent blocks arrived. Hashrate moves first. Difficulty follows at the next retarget, so the two can be out of step for up to two weeks. Convert units with the hashrate converter, or read more in the hashrate guide.
How has Bitcoin difficulty changed over time?
It started at 1, the minimum, when the first block was mined. It has climbed by many powers of ten since, because mining moved from laptop CPUs to graphics cards, then to purpose-built ASIC machines.
From difficulty 1 to today, one step per ×10
First block
difficulty 1
Latest block (live)
132.8 trillion
about 14.1 powers of ten higher
The long-run trend is up, but it isn’t a straight line. Difficulty drops when miners switch off: after a price fall, after a halving cuts rewards, or when a whole region stops mining at once, as happened with China’s mining ban in 2021. The full history is on mempool.space’s hashrate and difficulty chart.
What does difficulty mean for miners?
A miner’s expected income is their share of the network’s hashrate times the rewards. If difficulty rises 10% and your machine stays the same, you should expect about 9% less bitcoin per day. Drag the slider to see it.
What happens when miners join or leave
2,016 blocks take
9.3 days
Difficulty then
×1.50
An unchanged miner earns
×0.67
Simplified: one adjustment, steady hashrate. Real retargets compare the last 2,016 blocks with two weeks and can move difficulty by at most 4× either way.
0.0000004515BTC
Per TH/s per day (live estimate)
What 1 TH/s of hashing earns on average today, before pool fees and power. Miners call this hashprice.
↑ difficulty
Same machine, less bitcoin
Each rise shrinks every miner’s slice. Older, less efficient machines are the first to stop paying for their power.
↓ difficulty
Those still running earn more
When miners switch off, the ones left get a bigger share after the next retarget.
That’s why home mining is so hard to make pay. Hashrate keeps growing, so a machine’s output falls over its life. The profit calculator and the guide to whether mining is profitable run the numbers.
How does difficulty affect your CloudMineCrypto estimate?
In CloudMineCrypto you don’t need a machine, and you mine for free: the free plan, ads, games, offers and daily check-ins all add plans, and your BTC balance grows while they run. Paid plans are an optional add-on for more speed. The estimate uses the same share idea as real mining: your plan’s hashrate divided by the network’s, times 6 blocks an hour, times the block reward.
If the network hashrate changed, what would a plan earn?
Free plan
4.6 GH/s · one 8-hour run
Ad, game or check-in plan
7.4 GH/s · one 24-hour run
Your share of the network changes by ×0.83, and so does the estimate.
Live inputs, updated hourly. Estimates before boosts, not guaranteed. The app’s estimate follows the network hashrate figure, which is refreshed regularly, so it doesn’t wait for the next retarget.
Difficulty isn’t an input, but it moves with the network hashrate that is. When more hashrate joins, your share falls, and so does the estimate. When hashrate leaves, the same plan earns a little more. Live figures for every plan are in how much bitcoin will I earn, and the reward rules have the full details. Rewards are estimates and aren’t guaranteed. A plan doesn’t give you ownership of any mining hardware.
What do people get wrong about mining difficulty?
Someone sets the difficulty.
Nobody does. Every node works it out from the timestamps of the last 2,016 blocks, and a block with the wrong target is rejected.
It changes every two weeks, on a schedule.
It changes every 2,016 blocks. Two weeks is only the aim, so the date drifts with block speed.
More miners means more bitcoin gets issued.
Only briefly, until the next retarget. After that the pace goes back to about 10 minutes and the issuance schedule holds.
One adjustment fixes the block time straight away.
It averages the whole period. A change partway through is only partly corrected, and the next retarget finishes it. Try it in the dial at the top.
Difficulty tells you where the price is going.
It tells you how much hashing happened recently. Miners react to price, but difficulty trails them by up to two weeks.
A 10-minute average means a block every 10 minutes.
Block gaps are random. Gaps of a minute or of an hour both happen; the average is what difficulty steers.
New to this? Start with how Bitcoin mining works and proof of work, or look up any term in the glossary.
Frequently asked questions
What is Bitcoin mining difficulty?
A number that says how hard it is to find a valid block, compared with the easiest target the rules allow (difficulty 1). The network adjusts it every 2,016 blocks so blocks keep arriving about every 10 minutes.
How often does Bitcoin difficulty adjust?
Every 2,016 blocks. At 10 minutes per block that’s about two weeks, but the real gap depends on how fast blocks come, so it can be a few days earlier or later.
When is the next Bitcoin difficulty adjustment?
The live dial at the top of this page shows the estimated date, blocks left and expected change, from mempool.space data refreshed every 10 minutes. The date is an estimate because block times are random.
How much can difficulty change at once?
At most 4 times up or 4 times down in one adjustment. In practice changes are usually a few percent, because hashrate rarely moves that fast in two weeks.
Does higher difficulty mean fewer bitcoin are mined?
No. Difficulty keeps the pace at about one block every 10 minutes, so issuance follows the schedule whatever the difficulty. Higher difficulty means each miner gets a smaller share of the same rewards.
How is difficulty related to hashrate?
Network hashrate is roughly difficulty × 2³² ÷ 600 hashes per second. Difficulty follows hashrate with a delay of up to one period, since it only changes at retargets.
Does mining difficulty affect CloudMineCrypto rewards?
Indirectly, and you never have to manage it: the free plan, ads, games, offers and daily check-ins keep adding plans either way. The app’s estimate uses your plan’s share of the network hashrate, 6 blocks an hour and the block reward. When network hashrate rises, your share and your estimate go down. Rewards are estimates and aren’t guaranteed.
Sources and further reading
- Difficulty · Bitcoin Wiki
- Block chain guide: proof of work and target · Bitcoin Developer Guide
- Mining guide · Bitcoin Developer Guide
- Bitcoin: A Peer-to-Peer Electronic Cash System · Satoshi Nakamoto
- Hashrate and difficulty chart · mempool.space
- Mining dashboard: hashrate, difficulty, pools · mempool.space
Live figures on this page (network hashrate, block reward, BTC price) come from the CloudMineCrypto API, refreshed hourly, and are labelled where they appear. This guide is educational and not financial advice. CloudMineCrypto is not an investment product; rewards in the app are estimates and aren’t guaranteed.
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