# What is the exact data structure of each block?

is there any document / diagram describing Ethereum block structure in similar way as https://en.bitcoin.it/wiki/Block?

I know I can find implementation at https://github.com/ethereum/pyethereum/blob/develop/ethereum/blocks.py but I am still missing some information as bytesize and similar...

Yes, the Ethereum Yellow Paper (YP) and related Ethereum block architecture.

Here are the main pieces of a block and the YP has all the sizes:

4.3. The Block. The block in Ethereum is the collection of relevant pieces of information (known as the block header), H, together with information corresponding to the comprised transactions, T, and a set of other block headers U that are known to have a parent equal to the present block’s parent’s parent.

Here's an illusatration adapted from another answer -> definitions summarised from the yellow paper:

See also Equation (35) of the yellow paper. On github here, Latex format:

The component types are defined thus:
$$\begin{array}[t]{lclclcl} H_p \in \mathbb{B}_{32} & \wedge & H_o \in \mathbb{B}_{32} & \wedge & H_c \in \mathbb{B}_{20} & \wedge \\ H_r \in \mathbb{B}_{32} & \wedge & H_t \in \mathbb{B}_{32} & \wedge & H_e \in \mathbb{B}_{32} & \wedge \\ H_b \in \mathbb{B}_{256} & \wedge & H_d \in \mathbb{P} & \wedge & H_i \in \mathbb{P} & \wedge \\ H_l \in \mathbb{P} & \wedge & H_g \in \mathbb{P} & \wedge & H_s \in \mathbb{P}_{256} & \wedge \\ H_x \in \mathbb{B} & \wedge & H_m \in \mathbb{B}_{32} & \wedge & H_n \in \mathbb{B}_{8} \end{array}$$

where
$$\mathbb{B}_n = \{ B: B \in \mathbb{B} \wedge \lVert B \rVert = n \}$$