Protocol Parameters

Protocol parameters define the network's rules — fee calculations, size limits, deposits, and Plutus execution costs. The transaction builder fetches these automatically, but you can also query them directly.

Query Parameters

import { preprod, Client } from "@evolution-sdk/evolution"

const client = Client.make(preprod)
  .withBlockfrost({
    baseUrl: "https://cardano-preprod.blockfrost.io/api/v0",
    projectId: process.env.BLOCKFROST_API_KEY!
  })
  .withSeed({ mnemonic: process.env.WALLET_MNEMONIC!, accountIndex: 0 })

const params = await client.getProtocolParameters()

console.log("Min fee coefficient:", params.minFeeA)
console.log("Min fee constant:", params.minFeeB)
console.log("Max tx size:", params.maxTxSize)
console.log("Key deposit:", params.keyDeposit)
console.log("Pool deposit:", params.poolDeposit)

Key Parameters

Parameter	Description	Typical Value
minFeeA	Fee per byte coefficient	44
minFeeB	Base fee constant	155381
maxTxSize	Maximum transaction size (bytes)	16384
keyDeposit	Stake key registration deposit	2000000 (2 ADA)
poolDeposit	Pool registration deposit	500000000 (500 ADA)
coinsPerUtxoByte	Minimum ADA per UTxO byte	4310
collateralPercentage	Collateral percentage for scripts	150
priceMem	Plutus memory cost coefficient	0.0577
priceStep	Plutus CPU cost coefficient	0.0000721

Override in Build Options

You can provide custom protocol parameters when building transactions:

import { Address, Assets, preprod, Client } from "@evolution-sdk/evolution"

const client = Client.make(preprod)
  .withBlockfrost({
    baseUrl: "https://cardano-preprod.blockfrost.io/api/v0",
    projectId: process.env.BLOCKFROST_API_KEY!
  })
  .withSeed({ mnemonic: process.env.WALLET_MNEMONIC!, accountIndex: 0 })

declare const customParams: any

const tx = await client
  .newTx()
  .payToAddress({
    address: Address.fromBech32("addr_test1vrm9x2dgvdau8vckj4duc89m638t8djmluqw5pdrFollw8qd9k63"),
    assets: Assets.fromLovelace(2_000_000n)
  })
  .build({ protocolParameters: customParams })

Next Steps

• Transaction Status — Check confirmation status
• UTxOs — Query unspent outputs