What does hash lower than a bitcoin target mean with example – part 1

By | April 5, 2015

So you’ve Googled bitcoin target, read a whole bunch of stuff but still don’t get it and want to see real examples for comparisons. You’ve come to the right place. I learn best with examples so here goes.

From Bitcoin wikipediaThe target is a 256-bit number (extremely large) that all Bitcoin clients share. The SHA-256 hash of a block’s header must be lower than or equal to the current target for the block to be accepted by the network. The lower the target, the more difficult it is to generate a block.

If this is hard for you to visualize try this.

The current Bitcoin target, or hash target can be obtained from: http://blockexplorer.com/q/hextarget

You’ll notice it is a 256 bit number (from the quoted wikipedia text above) but represented in hexidecimal meaning it is only 64 characters long. (4 bits for 1 hex character so 256 bits/4 = 64 characters).

Let’s take for example a hash target of: 000000000000000051ABA2000000000000000000000000000000000000000000 which I got from https://www.bcoinnews.com/part-2-bitcoin-difficulty-hash-target. (This site helped me understand it).

Now if you convert this to decimal (I use http://www.asciitohex.com/) you get: 2.0025533784511E+57 which is a pretty big number. You then need to generate a hash target that is lower than this number.

Bitcoinnews talks about “So, if you have a hash result with 13 zeroes and “B” “0000000000000B” you did not solve a block”. What this really means is if you add zero’s after the hash result to pad the hex to 64 chars you’ll get: 0000000000000B00000000000000000000000000000000000000000000000000 which is 1.7676318486849E+61 in decimal.

1.7676318486849E+61 is not lower than 2.0025533784511E+57 so you’re attempt is … no good!

The next example yeilds: 0000000000000000A00000000000000000000000000000000000000000000000 which gives 3.9231885846167E+57. Again, 3.92 is greater than 2.00 (the exponents are the same here so we can ignore).

However, 0000000000000000400000000000000000000000000000000000000000000000 gives: 1.5692754338467E+57 which is indeed lower than the target which means you have solved the block… so hurry up and submit it and get your reward!

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