user21134: 
I have read that Previous Block hash takes around 32 bytes in the Block Header. Since it is a SHA256 hash which is 64 characters long, shouldn't it take 64 bytes as well? Similarly, Merkle root and other parameters.
Take a look at the following:
    010000009500c43a25c624520b5100adf82cb9f9da72fd2447a496bc600b0000000000006cd862370395dedf1da2841ccda0fc489e3039de5f1ccddef0e834991a65600ea6c8cb4db3936a1ae3143991
Length: 160
Apparently, it is x2 of what is actually written everywhere.
What kind of encoding is used here?

user24925: That is hex encoding, two ASCII characters per byte. 
SHA256 output is 32 bytes, or 64 characters when hex encoded. 

21134: <p><a href="https://i.stack.imgur.com/0VQfB.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/0VQfB.png" alt="Bitcoin Block Header"></a></p>

<p>I have read that Previous Block hash takes around 32 bytes in the Block Header. Since it is a SHA256 hash which is 64 characters long, shouldn't it take 64 bytes as well? Similarly, Merkle root and other parameters.</p>

<p>Take a look at the following:
    010000009500c43a25c624520b5100adf82cb9f9da72fd2447a496bc600b0000000000006cd862370395dedf1da2841ccda0fc489e3039de5f1ccddef0e834991a65600ea6c8cb4db3936a1ae3143991</p>

<p>Length: 160</p>

<p>Apparently, it is x2 of what is actually written everywhere.</p>

<p>What kind of encoding is used here?</p>
 24925: <p>That is hex encoding, two ASCII characters per byte. </p>

<p>SHA256 output is 32 bytes, or 64 characters when hex encoded. </p>
