Layer-two rollups compress many transactions off-chain and post a single summary to Ethereum mainnet, but that summary still consumes L1 gas. That raises the practical question: who ultimately pays the miner fees for the L1 posts? The short answer is users pay in aggregate, but the path of payment varies by design. Vitalik Buterin Ethereum Foundation explains that rollups reduce per-transaction L1 gas by batching, but the costs of the batch still must be covered. In practice, sequencers or rollup operators pay the immediate L1 gas when publishing a batch and then recover those costs through fees charged to users on the rollup or through other economic arrangements.
How fees are collected and passed on
Different rollup implementations describe slightly different flows. In optimistic rollups like Arbitrum, the architecture described by Steven Goldfeder Offchain Labs and Ed Felten Princeton shows the sequencer assembles transactions into a batch, posts calldata to Ethereum, and pays the on-chain gas at that moment. The sequencer then charges users an L2 transaction fee that is designed to cover both the sequencer’s operational cost and the amortized portion of the L1 gas used by each transaction. Optimism PBC documentation likewise describes a model where users pay fees denominated for L2 execution and settlement, and those fees are routed to the operator or fee pool that funds on-chain publishing.
For zk-rollups, StarkWare materials authored by Eli Ben-Sasson StarkWare and colleagues explain that a prover generates a succinct proof and an operator publishes the proof and compressed calldata on L1. The prover or operator pays the gas to post the proof and calldata; the protocol economics then allocate that cost back to users through transaction fees. Many zk-rollups make the cost per user lower because calldata is highly compressed, but the economic principle remains: someone must fund the L1 transaction and the system design determines how that cost is billed.
Variations, incentives, and consequences
There are important variations and consequences to who fronts the gas. Some rollup operators temporarily subsidize fees to improve user experience and adoption, absorbing L1 costs themselves or paying from treasury funds. This can create short-term centralization and fee opacity because users do not directly see the true L1 cost per transaction. Conversely, transparent fee markets where users directly pay L2 fees that include an explicit L1 component produce clearer economic signals and can make the rollup more sustainable long term. The Ethereum Foundation commentary by Vitalik Buterin highlights that transparent accounting helps maintain decentralization incentives.
Environmental and territorial nuances also matter. Because rollups reduce aggregate gas per user, the per-transaction energy and resource footprint on L1 declines, which has environmental implications compared with all activity on mainnet. For users in regions with high fiat-to-crypto conversion costs, subsidized fees can materially affect access, while shifting the burden onto protocol treasuries or token holders creates different distributional impacts.
In short, the sequencer or operator pays L1 gas upfront, and users ultimately bear the cost through L2 fees unless the operator subsidizes those costs. The exact balance between immediate operator payment and user fee recovery depends on protocol design choices documented by the rollup teams and researchers cited above. Understanding those choices is crucial for evaluating user costs, decentralization trade-offs, and long-term sustainability.