How to calculate scriptPubkey? Given an address (i.e. 1BnPVV5Tt25cxbDg6DqoxJunjSL8reCGz6), how can I calculate its scriptPubKey in order to build a transaction?
I assume you want to integrate it into a P2PKH tx.
You would have to base58decode the address, and then remove the checksum and the network byte. Then you can integrate it into a P2PKH tx in the std. way:
76 A9 14 &lt;20 Bytes&gt; 88 AC
I have two references with some code examples in C and python, that helped me at the time, when I had the same question :-)

https://bitcointalk.org/index.php?topic=1543429.0
https://bitcointalk.org/index.php?topic=1026.0

and some online &quot;play tools&quot; to verify:

http://gobittest.appspot.com/Address
http://lenschulwitz.com/base58