The priority fee (commonly called a miner tip or validator tip) is the per-unit-of-gas payment above the base fee that a transaction sender voluntarily offers to the Ethereum block proposer — introduced alongside EIP-1559 in the August 2021 London hard fork — which goes entirely to the validator rather than being burned, serves as the primary mechanism by which users signal urgency and compete for faster transaction inclusion when mempool congestion would otherwise cause delays, and forms the basis of the MEV (Maximum Extractable Value) economy where sophisticated searchers, arbitrageurs, and block builders compete to order transactions profitably within blocks. Unlike the base fee (which is protocol-determined and burned), the priority fee is user-determined, variable across transactions in the same block, and creates an economic incentive for validators to include transactions promptly — essentially the “queue-jumping” fee in Ethereum’s transaction ordering system.
EIP-1559 Fee Structure Recap
“`
Total Gas Fee = Gas Used × (Base Fee + Priority Fee)
Base Fee:
- Set by protocol
Burned (removed from ETH supply)
Adjusts each block based on utilization
Priority Fee (Tip):
- Set by user
Paid to block validator/proposer
Competitive signal for inclusion speed
“`
How Priority Fee Works
Normal Conditions
- Priority fee of 0.5–2 gwei is sufficient for next-block inclusion
- Almost all transactions confirm within 1–3 blocks regardless of tip
- Priority fee is a small fraction of total gas cost
Congested Conditions
- Mempool fills with thousands of pending transactions
- Validators select transactions to maximize fee income
- Users with higher priority fees get included first
- Priority fees spike to 50–500+ gwei during extreme events
Priority Fee During NFT Mints (Example)
Popular NFT mint: 50,000 users want to mint simultaneously
Block can fit: ~200 transactions
Result: 49,800+ transactions compete via priority fee bidding
Base fee: 500 gwei (spiked from congestion)
Priority fees paid: 100–1,000 gwei (additional on top of base fee)
Winner: Wallet with highest max fee and priority fee gets minted
Loser: Others wait multiple blocks or fail
“`
MEV and Priority Fees
The priority fee is the economic foundation of MEV (Maximum Extractable Value) and the PBS (Proposer-Builder Separation) ecosystem:
Why MEV Searchers Pay High Tips
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Arbitrage opportunity: $10,000 profit available between Uniswap and Curve
Searcher’s max profitable tip: up to $9,999
Typical tip paid: 90% of profit → $9,000 to validator
Searcher keeps: $1,000
Without high tip: Another searcher outbids and captures the opportunity
“`
Priority Fee as MEV Revenue
- Consensus rewards: Fixed PoS block rewards (~0.02 ETH/block)
- Execution rewards: Priority fees + MEV payments from block builders
During high-activity periods, execution rewards (priority fees + MEV) dwarf consensus rewards — sometimes 10–50× larger.
maxFeePerGas vs. maxPriorityFeePerGas
EIP-1559 transactions specify both:
“`
maxFeePerGas: User’s absolute maximum per-gas fee (hard cap)
maxPriorityFeePerGas: Desired tip to validator
Effective gas price = min(maxFeePerGas, baseFee + maxPriorityFeePerGas)
Effective tip = min(maxPriorityFeePerGas, maxFeePerGas – baseFee)
“`
Example
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User sets: maxFeePerGas = 120 gwei, maxPriorityFeePerGas = 5 gwei
Current base fee: 100 gwei
Effective tip = min(5, 120 – 100) = min(5, 20) = 5 gwei ✓
User pays: 100 + 5 = 105 gwei
Refund: 120 – 105 = 15 gwei per gas refunded
If base fee spikes to 118 gwei:
Effective tip = min(5, 120 – 118) = min(5, 2) = 2 gwei
User pays: 118 + 2 = 120 gwei (at cap)
No refund; transaction may be delayed or replaced
“`
Priority Fee in Layer 2
On Ethereum L2s (Optimism, Arbitrum, Base):
Sequencer Ordering
- Priority fee paid on L2 goes to sequencer (like validator tip on L1)
- During normal conditions, all transactions are included in FIFO order regardless of tip
- Priority fee on L2 typically very low (< 0.01 gwei)
L2 to L1 Cost Transmission
- L1 data fee is based on L1 base fee at time of L2 batch submission
- After EIP-4844 (March 2024): L1 data fee dropped 99%+ for most L2s
History
- Pre-2021: Ethereum uses single “gas price” — all paid to miner; users over-tip to ensure inclusion
- 2018: EIP-1559 first proposed; envisions priority fee as explicit separation
- 2021 Aug: EIP-1559 activated (London hard fork); priority fee becomes explicit
- 2021–2022: NFT era; priority fees spike to hundreds of gwei during popular mints
- 2022 Sep: The Merge; validators replace miners; priority fees go to validators
- 2022: MEV-Boost (PBS) becomes dominant; ~90% of Ethereum blocks built by specialized builders; priority fee economy matures
- 2024: Blob transactions (EIP-4844) reduce L2 data costs; priority fees on L1 remain MEV-driven