queryLedgerState/protocolParameters

Query the current protocol parameters

Query the current Cardano protocol parameters including fees, limits, and governance settings.

Request

{
  "jsonrpc": "2.0",
  "method": "queryLedgerState/protocolParameters"
}

No parameters required.

Response

{
  "jsonrpc": "2.0",
  "method": "queryLedgerState/protocolParameters",
  "result": {
    "minFeeCoefficient": 44,
    "minFeeConstant": { "ada": { "lovelace": 155381 } },
    "minUtxoDepositCoefficient": 4310,
    "maxBlockBodySize": { "bytes": 90112 },
    "maxBlockHeaderSize": { "bytes": 1100 },
    "maxTransactionSize": { "bytes": 16384 },
    "maxValueSize": { "bytes": 5000 },
    "stakeCredentialDeposit": { "ada": { "lovelace": 2000000 } },
    "stakePoolDeposit": { "ada": { "lovelace": 500000000 } },
    "stakePoolRetirementEpochBound": 18,
    "desiredNumberOfStakePools": 500,
    "stakePoolPledgeInfluence": "3/10",
    "monetaryExpansion": "3/1000",
    "treasuryExpansion": "1/5",
    "version": { "major": 10, "minor": 0 },
    "minStakePoolCost": { "ada": { "lovelace": 170000000 } },
    "collateralPercentage": 150,
    "maxCollateralInputs": 3,
    "plutusCostModels": { ... },
    "scriptExecutionPrices": {
      "memory": "577/10000",
      "cpu": "721/10000000"
    },
    "maxExecutionUnitsPerTransaction": {
      "memory": 14000000,
      "cpu": 10000000000
    },
    "maxExecutionUnitsPerBlock": {
      "memory": 62000000,
      "cpu": 20000000000
    }
  }
}

Key Parameters

Fee Calculation

Parameter	Description
`minFeeCoefficient`	Fee per byte (44 lovelace/byte)
`minFeeConstant`	Base fee (~0.155 ADA)
`collateralPercentage`	Script collateral requirement (150%)

Fee formula: fee = minFeeConstant + (minFeeCoefficient × txSize)

Transaction Limits

Parameter	Value	Description
`maxTransactionSize`	16,384 bytes	Maximum transaction size
`maxValueSize`	5,000 bytes	Maximum output value size
`maxCollateralInputs`	3	Max collateral UTxOs

Script Execution

Parameter	Description
`scriptExecutionPrices.memory`	Price per memory unit
`scriptExecutionPrices.cpu`	Price per CPU step
`maxExecutionUnitsPerTransaction`	Max execution units per tx
`maxExecutionUnitsPerBlock`	Max execution units per block

Staking

Parameter	Value	Description
`stakeCredentialDeposit`	2 ADA	Deposit to register stake key
`stakePoolDeposit`	500 ADA	Deposit to register pool
`desiredNumberOfStakePools`	500	Target pool count (k parameter)

Code Examples

const response = await fetch('https://api.nacho.builders/v1/ogmios', {
method: 'POST',
headers: {
  'Content-Type': 'application/json',
  'apikey': process.env.NACHO_API_KEY
},
body: JSON.stringify({
  jsonrpc: '2.0',
  method: 'queryLedgerState/protocolParameters'
})
});

const { result } = await response.json();

// Calculate minimum fee for a transaction
function calculateMinFee(txSizeBytes) {
const coefficient = result.minFeeCoefficient;
const constant = result.minFeeConstant.ada.lovelace;
return constant + (coefficient * txSizeBytes);
}

console.log('Min fee for 300 byte tx:', calculateMinFee(300), 'lovelace');

Use Cases

Fee calculation - Calculate transaction fees before building
Script validation - Check execution unit limits
Wallet configuration - Get minimum UTxO values
Governance - Monitor protocol parameter changes

Full Ogmios API Reference

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