user50821: What is the typical bytesize range for an extended public key? 
An extended private key? 

user48884: An extended public or private key is always 78 bytes of data. When Base58 Check encoded, this results in a string that is up to 112 characters in size.
The format of the data is defined in BIP 32.

50821: <p>What is the typical bytesize range for an extended public key? </p>

<p>An extended private key? </p>
 48884: <p>An extended public or private key is always 78 bytes of data. When Base58 Check encoded, this results in a string that is up to 112 characters in size.</p>

<p>The format of the data is defined in <a href="https://github.com/bitcoin/bips/blob/master/bip-0032.mediawiki#serialization-format" rel="noreferrer">BIP 32</a>.</p>
