Updated fee constants in Delphi?

Question

I am using the following formula and associated constants to calculate fees: https://tezos.gitlab.io/protocols/003_PsddFKi3.html#more-details-on-fees-and-cost-model

Also referenced here: https://tezos.stackexchange.com/a/107/5237

Since the Delphi protocol upgrade my calculated fees result in transactions which often take 15-60 blocks to confirm, assuming because baker's de-prioritize transactions with fees too low.

The constants I was using before Delphi:

minimal_fees = 100 000 nanotez (100 mutez)
minimal_nanotez_per_gas_unit = 100 nanotez
minimal_nanotez_per_byte = 1000 nanotez (1 mutez) 

After Delphi:

minimal_nanotez_per_byte is given by the node, and is now 250 nanotez. Other values are the same (hard-coded).

My formula, using consumed_gas given by run_operation:

fee = minimal_fees + 
      (minimal_nanotez_per_gas_unit * consumed_gas) +
      (minimal_nanotez_per_byte * tx_size_in_bytes)
fee = fee * 1.05 // 5% padding

I added a somewhat arbitrary 5% padding (prior to Delphi) to resolve transactions occasionally not getting picked up by bakers within a reasonable time or sometimes not until they expire from the mempool. After Delphi I am seeing this happen more regularly despite the 5% added.

Is there a better formula or updated constants I should be using to calculate fees to ensure operations are confirmed consistently?

Answer 1

You should use gas_limit instead of consumed_gas in that calculation. gas_limit is often set a bit higher than consumed_gas (from the simulation). minimal_nanotez_per_byte have not changed to 250 nanotez, should still be 1000 nanotez (assuming baker default configuration). cost_per_byte has changed to 250 mutez, but this has nothing to do with the fee. It's used to determine the storage cost.