Protocol parameters

Protocol parameters on Cardano are the various settings that define the blockchain's behavior.

Let's delve into the protocol parameters using the Cardano CLI. Note that this time, we will be using the mainnet, as testnet environments may have different parameter values. Additionally, it's important to mention that the output is simplified as the cost models are collapsed.

$ cardano-cli query protocol-parameters --mainnet

> {
    "collateralPercentage": 150,
    "costModels": {
        "PlutusScriptV1": {...},
        "PlutusScriptV2": {...}
    },
    "decentralization": null,
    "executionUnitPrices": {
        "priceMemory": 5.77e-2,
        "priceSteps": 7.21e-5
    },
    "extraPraosEntropy": null,
    "maxBlockBodySize": 90112,
    "maxBlockExecutionUnits": {
        "memory": 62000000,
        "steps": 40000000000
    },
    "maxBlockHeaderSize": 1100,
    "maxCollateralInputs": 3,
    "maxTxExecutionUnits": {
        "memory": 14000000,
        "steps": 10000000000
    },
    "maxTxSize": 16384, 
    "maxValueSize": 5000,
    "minPoolCost": 340000000,
    "minUTxOValue": null,
    "monetaryExpansion": 3.0e-3,
    "poolPledgeInfluence": 0.3,
    "poolRetireMaxEpoch": 18,
    "protocolVersion": {
        "major": 7,
        "minor": 0
    },
    "stakeAddressDeposit": 2000000,
    "stakePoolDeposit": 500000000,
    "stakePoolTargetNum": 500,
    "treasuryCut": 0.2,
    "txFeeFixed": 155381,
    "txFeePerByte": 44,
    "utxoCostPerByte": 4310,
    "utxoCostPerWord": null
}

The CLI retrieves the protocol parameters from the ledger state. This implies that these parameters are currently active, along with their corresponding values. Please note that any parameters set to null have been deprecated.

Protocol parameters can be updated via an update proposal.

Alongside protocol parameters, there are global constants. Unlike protocol parameters, global constants can only be updated through a software update, which always involves incrementing the protocol version. An increase in the major version indicates a hard fork, while the minor version represents a soft fork, allowing old software to validate but not produce new blocks.

SlotsPerEpoch
SlotsPerKESPeriod
MaxKESEvolutions
StabilityWindow
RandomnessStabilisationWindow
Quorum
MaxMajorPV
ActiveSlotCoeff
NetworkId
MaxLovelaceSupply
securityParam
slotLength

Below you will find a description of the protocol parameters and global constants:

	Description	Value
NetworkId	Determines the expected network (mainnet or testnet)	mainnet
MaxLovelaceSupply	The total number of lovelace in the system	45000000000000000
SlotsPerEpoch	The number of slots in an epoch	432000
k	The security parameter, which defines the number of blocks required for the blockchain to be considered final, preventing any further rollback (ie, the maximum allowable length of any chain fork)	2160
ActiveSlotCoeff	The fraction of slots, denoted as 'f' in the Praos paper, represents the average proportion of slots that a block will contain	0.05
slotLength	The length of each slot (in seconds)	1
txFeeFixed	Base transaction fee (in lovelace)	155381
txFeePerByte	Additional transaction fee per byte of data (in lovelace)	44
maxTxSize	Maximum transaction size in bytes	16384
maxBlockBodySize	Maximum block size in bytes	90112
maxBlockHeaderSize	Maximum block header size in bytes	1100
maxValueSize	The maximum serialized length (in bytes) of a multi-asset value (token bundle) in a transaction output	5000
Quorum	The number of the Genesis delegate keys that must endorse an update proposal	5
protocolVersion major minor	Current protocol version	7.0
MaxMajorPV	If the major component of the protocol version is larger than MaxMajorPV, there is an ObsoleteNode failure	Halts below 7.0 nodes
StabilityWindow	The number of slots needed for a block to become stable, defined as 3k/f	3k/f
stakeAddressDeposit	Deposit amount in lovelace required to register stake credential	2000000
stakePoolDeposit	Deposit amount in lovelace required to register a stake pool	500000000
stakePoolTargetNum	The optimal number of saturated stake pools. Impacts saturation threshold, encouraging growth in the number of stake pools	500
decentralization	Controls how many slots are governed by the genesis nodes via OBFT and which slots are open to any registered stake pool	Deprecated Shelley - Alonzo: [0-1] Babbage: Null
SlotsPerKESPeriod	Defines after how many slots a pool's operational key pair evolves (key evolving signatures)	129600
MaxKESEvolutions	The maximum number of times a KES key pair can evolve before a new KES key pair is generated from the master keys	62
poolRetireMaxEpoch	Maximum number of epochs within which a pool can be announced to retire, starting from the next epoch	18
minPoolCost	Minimum pool cost per epoch (in lovelace), which enables pledge effect	340000000
minUTxOValue	The minimum ada value that a transaction output must hold (during the Shelley era)	Deprecated
utxoCostPerWord	During the Mary, Allegra, and Alonzo eras, this parameter determined the minimum ada value required for a transaction output to support native assets (in the Mary and Allegra eras) and datum hashes (in the Alonzo era)	Deprecated
utxoCostPerByte	In the Babbage era, transaction outputs are required to contain at least (160 +	serialized_output
treasuryCut	Proportion of the reward pot that will move to the treasury at each rewards distribution	0.2
monetaryExpansion	Every epoch, the total amount of ada in circulation is increased by monetaryExpanision % of the ada reserves and is moved to the rewards pot	3.0e-3 (.003)
poolPledgeInfluence	Determines stake pool owner-stake influence on pool rewards	0.3
costModels PlutusV1 PlutusV2	Every phase-2 scripting language converts the calculated execution cost into a number of ExUnits using a cost model, which depends on the language	PV1 PV2
executionUnitPrices priceMemory priceSteps	Prices consist of two rational numbers that correspond to the components of ExUnits: the price per unit of memory and price per reduction step	priceMemory: 5.77e-2 (.0577) priceSteps: 7.21e-5 (.0000721)
maxBlockExecutionUnits memory steps	Maximum ExUnits allowed in a block	memory: 62000000 steps: 40000000000
collateralPercentage	The percentage of the total transaction fee, its collateral must (at minimum) cover	150
maxCollateralInputs	Limits the total number of collateral inputs, and thus the total number of additional signatures that must be checked during validation	3
extraPraosEntropy	This provides additional certainty that the blockchain has not been compromised by the seed key holders. Redundant once the system is sufficiently decentralized	Depracated See https://iohk.io/en/blog/posts/2021/03/29/the-secure-transition-to-decentralization/

Resources

• Cardano ledger repository contains the formal specifications, executable models, and implementations of the Cardano ledger.

• Cardano improvement proposal 9

• Cardano improvement proposal 28

• Cardano improvement proposal 55

• Original implementation, Cardano-SL https://github.com/serokell/cardano-sl/blob/master/docs/configuration.md