cardano-protocol-params

• Fetching fresh protocol parameters
• Understanding fee calculation inputs
• Debugging min-UTxO or execution budget issues
• Comparing params across networks

• Always fetch fresh params for the target network
• Never assume mainnet params apply to testnets
• Keep pparams.json with tx artifacts for reproducibility

Fee calculation

```

minFeeA: 44 # lovelace per byte

minFeeB: 155381 # base fee in lovelace

```

Formula: fee = minFeeA * txSize + minFeeB

Min UTxO

```

coinsPerUTxOByte: 4310 # lovelace per byte of UTxO

```

Minimum ADA required = size of UTxO (including datum) × coinsPerUTxOByte

Execution units (Plutus)

```

maxTxExecutionUnits:

steps: 10000000000 # CPU budget

memory: 10000000 # Memory budget

executionUnitPrices:

priceSteps: 0.0000721 # lovelace per step

priceMemory: 0.0577 # lovelace per memory unit

```

Reference scripts

```

minFeeRefScriptCostPerByte: 15 # Cost for using reference scripts

```

Fetch parameters

```bash

# Preprod

cardano-cli conway query protocol-parameters \

--testnet-magic 1 \

--out-file pparams-preprod.json

# Mainnet

cardano-cli conway query protocol-parameters \

--mainnet \

--out-file pparams-mainnet.json

```

Extract key values

```bash

# Using jq

cat pparams.json | jq '{

minFeeA: .txFeePerByte,

minFeeB: .txFeeFixed,

coinsPerUTxOByte: .utxoCostPerByte,

maxTxSize: .maxTxSize,

maxValSize: .maxValueSize

}'

```

Calculate min-UTxO for output

```bash

# Approximate: base ~160 bytes + datum size

# For simple ADA-only output: ~1 ADA minimum

# For output with tokens: varies by token count/names

```

Example: Debug "UTxO too small" error

Problem: Transaction fails with min-UTxO error

Response:

```bash

# 1. Fetch current params

cardano-cli conway query protocol-parameters \

--testnet-magic 1 \

--out-file pparams.json

# 2. Check coinsPerUTxOByte

cat pparams.json | jq .utxoCostPerByte

# Result: 4310

# 3. Estimate min-UTxO for your output

# Simple ADA output: ~160 bytes × 4310 = ~690,000 lovelace

# With inline datum: add datum size × 4310

# With tokens: add ~30 bytes per token

# 4. Solution: increase output amount above minimum

```

Example: Estimate script execution cost

Problem: Need to budget for Plutus script

Response:

```bash

# 1. Get execution prices

cat pparams.json | jq '{

priceSteps: .executionUnitPrices.priceSteps,

priceMemory: .executionUnitPrices.priceMemory

}'

# 2. If script uses 1M steps and 100K memory:

# Cost = (1000000 × 0.0000721) + (100000 × 0.0577)

# Cost = 72.1 + 5770 = 5842.1 lovelace (~0.006 ADA)

# 3. Add to base tx fee for total

```

```

Mainnet: (no flag, use --mainnet)

Preprod: --testnet-magic 1

Preview: --testnet-magic 2

```

• Protocol params are public, no secrets involved
• Always verify you're querying the intended network
• Store pparams with tx artifacts for debugging

• shared/PRINCIPLES.md
• [Cardano Protocol Parameters](https://docs.cardano.org)