Protocol Parameters Reference

Cardano protocol parameters control fees, block sizes, staking mechanics, script execution budgets, and governance. Every one of them is mutable through a ParameterChange governance action, so the values below are not constants — always query a node for truth.

Mainnet values in this page were read from mainnet epoch 646. They are included to give a sense of scale, not as defaults. Re-read them from a node before relying on any of them.

Querying Parameters

dugite-cli query protocol-parameters \
  --socket-path ./node.sock \
  --out-file protocol-params.json

The JSON key names in the tables below are the cardano-cli-compatible names that dugite-cli emits and accepts. They are not the Rust field names and they are not produced by serde — they are written by the N2C client decoder in crates/dugite-network/src/n2c_client.rs. Where cardano-cli accepts an older alias, both are listed.

Fee Parameters

The base transaction fee formula is:

fee = txFeePerByte * tx_size_in_bytes + txFeeFixed

Conway adds a tiered reference-script surcharge on top, growing geometrically with total reference-script size.

Minimum-UTxO is era-dispatched, not one formula. Dugite selects the per-era Haskell calculation from the protocol version in force (issue #919): flat minUTxOValue at PV ≤ 3; Mary scaledMinDeposit at PV 4; Alonzo (27 + size + dataHashSize) × coinsPerUTxOWord at PV 5–6; Babbage (160 + size) × coinsPerUTxOByte at PV ≥ 7. Key 17 therefore means coinsPerUTxOWord before Babbage and coinsPerUTxOByte from Babbage on.

Block Size Parameters

Staking Parameters

Monetary Policy

These three are exact rationals on the wire (CBOR tag 30), not floats. Dugite parses genesis values as exact Scientific and never through an f64 intermediate — a lossy parse here diverges the reward calculation.

Plutus Execution Parameters

maxValueSize is compared with a strict >, against a size computed with Haskell encodeMap semantics — indefinite-length CBOR map headers above 23 entries, definite at or below. Getting that wrong over-counts by one byte on large asset maps and produces a false Phase-1 rejection (issue #930).

Governance Parameters (Conway)

Voting Thresholds

The threshold parameters travel on the wire as two fixed-order arrays, not as individual keys: poolVotingThresholds (5 entries, CBOR key 25) and drepVotingThresholds (10 entries, CBOR key 26).

poolVotingThresholds — array order:

drepVotingThresholds — array order:

Which body votes on what

This is the ratification matrix Dugite implements, matching Haskell Conway.Rules.Ratify. "—" means that body does not vote on the action at all (it is not an abstention — the check is simply absent).

Two consequences worth internalising:

• There is no pvtPPEconomicGroup. The only SPO threshold for parameter changes is pvtPPSecurityGroup, and SPOs are excluded entirely from a parameter change that touches no security-tagged parameter.
• A parameter change spanning several groups must clear each group's DRep threshold, not just the highest one.

During the Conway bootstrap phase, DRep thresholds are treated as zero (always met) and only the SPO and committee checks bind.

CBOR keys for a ProtocolParamUpdate

Governance actions carry parameter changes as a sparse CBOR map keyed by integer. This is the complete table Dugite encodes and decodes.

Notes on asymmetry, because it bites:

• Keys 12–15 exist only in the pre-Conway (Shelley → Babbage) update shape. Dugite decodes them for historical replay; the Conway encoder never emits them, and the Conway decoder skips them.
• Keys 34–37 are the unreleased Dijkstra era. They decode but are not encoded.
• Key 30 is govActionDeposit and key 31 is dRepDeposit — the order is the opposite of what the alphabetical reading suggests, and swapping them silently produces a valid-looking but wrong proposal.

Encoder: crates/dugite-serialization/src/encode/protocol_params.rs. Decoders: crates/dugite-serialization/src/decode/era_conway.rs (Conway and later) and .../era_shelley.rs (pre-Conway).

N2C wire encoding of the current parameters

The GetCurrentPParams LocalStateQuery reply is not the sparse integer-keyed map above. It is a positional CBOR array(31), indices 0–30, matching Haskell's EncCBOR (ConwayPParams Identity ConwayEra). The two layouts are different and are not interchangeable.

Every index 0–30 is populated; there are no gaps and no Dijkstra slots. GetGenesisConfig uses a different, legacy Shelley-era layout — array(18) on N2C v16–v20 and array(17) on v21+.

Encoder: crates/dugite-node/src/node/n2c_query/encoding.rs (encode_protocol_params_cbor). Client-side decoder to cardano-cli JSON: crates/dugite-network/src/n2c_client.rs (parse_protocol_params_cbor).