Tool · Difficulty & emission

Bits, target and difficulty

Three ways to write how hard it is to find a block

Three ways to write how hard a block is

Bits 4 bytes, in the header

Difficulty vs. 0x1b00ffff

Target 256-bit number, hex

How bits encode the target

17 6a f3 a6

target = 0x6af3a6 × 256^{23 − 3} : the exponent says the target is 23 bytes long; the mantissa gives its first 3 bytes, the rest are zeros.

0000000000000000006af3a60000000000000000000000000000000000000000

Difficulty

40,157,376.49334089

The PowLimit target (difficulty 1) ÷ this target.

Target

0000000000000000006af3a60000000000000000000000000000000000000000

How small the target is, on a log scale from 1 to 2²⁵⁶

The target is about 2^182.7. A random 256-bit number lands below it about once in 1.13 × 10²² tries. Each step left on this bar is a doubling of difficulty. Expected work per block (chain work) is 2²⁵⁶ ÷ (target + 1) ≈ 2^73.3.

Pearl: nothing is compared with this target alone. A block wins when its certificate’s BLAKE3 ticket is at most target × the work in one tile, and the block hash is never checked against it.

Runs in your browser · nothing is sent src/lib/block.ts · btcd’s CompactToBig / BigToCompact

What it does

Type any one of the three and the other two follow:

Bits: the 4-byte compact form stored in every block header.
Target: the 256-bit number those bits stand for.
Difficulty: how many times smaller the target is than the easiest one allowed.

How to read it

Bits are a tiny floating-point number: the first byte (the exponent) is the target’s length in bytes, and the next three (the mantissa) are its first three bytes. Everything after them is zero.
The 32 boxes are the target written out in full. Amber boxes are the mantissa; the dim ones are leading zeros.
The bar uses a log scale: each step left halves the target and doubles the difficulty. A random 256-bit number lands below the target about once in 2^(256 − log₂ target) tries.
Typing a target or a difficulty rounds it to what bits can store (three significant bytes), so you may see a slightly different value come back.

Pearl specifics

Difficulty 1 is bits 0x1b00ffff, Pearl’s PowLimit (2²⁰⁸ − 1). Bitcoin’s difficulty 1 is 0x1d00ffff, which is above Pearl’s limit and invalid here. Pearl’s easiest target is 65,536 times smaller than Bitcoin’s.
Nothing in Pearl compares a hash with this target alone. A block wins when the BLAKE3 ticket in its certificate is at most target × the work in one tile. The block hash is never checked against it.
The target changes after every block (WTEMA), so consecutive blocks have slightly different bits.

Under the hood

Runs entirely in your browser: nothing you type is sent anywhere. The conversions are src/lib/block.ts, written to match btcd’s CompactToBig and BigToCompact and the node’s difficulty report. Unit tests check them against the research test vectors (bits → target → difficulty → work) and real mainnet headers.