What is the significance of uncle rate?

Some Ethereum sites show an uncle rate in decimal, another shows the uncle count per 25 blocks. If there are many or few uncles, how important is that to the network? Are there "warning" signs that it suggests?

1 Answer 1


Uncles occur when a valid block does not make it into the long-term consensus. These orphaned blocks can be caused by high network latency, so I would say that a dramatic increase in the uncle rate indicates that the block gas limit is too high, thus making the blocks too large to propagate efficiently. Alternatively, it could indicate some other slow down of block propagation, due to DDOS attacks or some other network interference.

  • can you please define a 'valid block'? means is it a block which has been prepared by and agreed upon by nodes to be hashed, or is it a successfully hased block? Jan 31, 2018 at 1:21
  • Nodes don't 'agree' to hash a block, each miner forms their own blocks individually. Valid in this sense means that the PoW on the block is valid Jan 31, 2018 at 4:59

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