Question: new_coins_per_byte & ref_script_coins_per_byte cost values to use

[gmoratorio]

I'm refactoring our CSL code from 11.5.0 to 12.1.0 and I've come across a few places where I'm not sure what we should use for cost values.
new_coins_per_byte
In our codebase we used 34482 for coins_per_utxo_word and I see in other places we have 4310 for coins_per_utxo_byte, but I'm not sure if
A. value for coins_per_utxo_word can be directly translated to coins_per_byte (or what the translation math should be) and
B. if our existing usage of 4310 in other places for coins_per_utxo_byte is the best value to use, or if there is a better recommended default

ref_script_coins_per_byte (now required to work with the script_size arg introduced in new_ref_input)
I found "minFeeRefScriptCostPerByte": 15 in our Stake Pool's conway-genesis.json file, but I'm not sure if this is the right value to use, and also ref_script_coins_per_byte expects an interval, so I'm not sure what the numerator and denominator should be in this case.

Any insights into cost values to use for new_coins_per_byte and ref_script_coins_per_byte or links to docs where these recommended values are stored would be very helpful.

Thanks in advance!

[lisicky]

It's a protocol parameter that can be updated on-chain by a governance action.

To get your latest protocol parameters, you can use:

1. cardano-cli
2. dbsync
3. Third-party services like Blockfrost, Koios, or Ogmios
4. Manually get them from cexplorer
5. Come up with something different

The difference between coins_per_utxo_word and coins_per_utxo_byte is that the coins_per_utxo_size parameter from protocol parameters was coins_per_utxo_word until the Babbage era, but since Babbage, it's coins_per_utxo_byte. We had both variants in the CSL to have a smooth transition between eras because initially, coins_per_utxo_byte was coins_per_utxo_word / 8. Up to this moment, coins_per_utxo_byte has not changed, but it might be changed in the future by a governance action.

[gmoratorio]

ah yes, fantastic, thank you. I see both coins_per_utxo_size and coins_per_utxo_word from Blockfrost.

For min_fee_ref_script_cost_per_byte (looks like the protocol param is currently 15), for the UnitInterval required by CSL do we just do numerator 15, denominator 1?

[lisicky]

@gmoratorio right

[gmoratorio]

Thanks so much for the help! Really useful info. Much appreciated.

[gmoratorio]

Thanks for the help!