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Ethereum Blob Fees: How EIP-7918 Changes Layer 2 Costs
A practical guide to the live fee-floor rule, its 1/16 parameter and what it does—and does not—mean for rollup costs.
Ethereum blob fees are the separate fee rollups pay to post data blobs to Ethereum, alongside ordinary execution gas. EIP-7918 adds a reserve-price rule: the blob base-fee rate cannot drift below a threshold tied to Ethereum’s Layer 1 execution base fee. The specified ratio is 1/16, but the market can still charge more when blob demand is high, and the rule does not set a rollup’s retail fee. EIP-7918 shipped with Fusaka, which activated on Ethereum mainnet on 3 December 2025.
How Ethereum blob fees work
EIP-4844 introduced a separate blob-gas accounting and fee market. A blob-carrying transaction pays for the blob gas it uses at the blob base fee, as well as the ordinary execution gas needed to include and process the transaction. These are related charges, but they are not the same meter.
Rollups that publish data in blobs therefore face a data-availability cost on Ethereum in addition to the execution cost of the L1 transaction that submits it. The blob base fee moves with blob demand: it can rise above its reserve level, while low demand would otherwise let it drift toward the protocol’s minimum of 1 wei.
That distinction matters when estimating costs. A low blob base fee does not mean the L1 submission is free, and a blob-price change does not translate mechanically into the fee an L2 user sees. For a separate look at execution-gas changes, see our Glamsterdam gas-testing guide.
What EIP-7918 changes
EIP-7918 changes how Ethereum updates excess_blob_gas, the value used by the blob-fee mechanism. When the blob-fee rate falls below a threshold linked to the execution base fee, the update stops subtracting the target blob gas. That lets excess blob gas—and consequently the blob base fee—recover toward the reserve instead of continuing to fall as if the data were nearly costless to supply.
The EIP sets BLOB_BASE_COST to 2**13. Compared with the GAS_PER_BLOB parameter in EIP-4844, that produces a reserve blob base-fee rate equal to 1/16 of the execution base-fee rate. The threshold is dynamic: it follows the L1 execution base fee rather than fixing a permanent price in ETH.
The 1/16 figure describes the protocol’s reserve-price relationship between two base-fee rates. It is not a promise that every blob transaction costs exactly 1/16 of an execution transaction, nor that a rollup’s total cost or user fee will move by that percentage.
Why Ethereum added a reserve price
The EIP identifies two reasons for the rule. First, a rollup’s total cost can include execution gas, proof verification and priority fees, not just the blob fee. If those other costs dominate, reducing the blob fee has little effect on the consumer’s all-in price. The blob auction can then lose a useful signal about demand and, under sustained low demand, settle at 1 wei before taking a long time to respond when usage returns.
Second, nodes perform computational work to validate blob-related KZG proofs. EIP-7918 uses the execution base fee as a protocol reference for the value of node computation, and sets a reserve price so blob consumers pay at least a relevant fraction of that compute-market rate. This is a pricing rule, not a precise measurement of each node’s costs.
EIP-7918 is a final core EIP and was included in Fusaka. The Ethereum Foundation’s mainnet announcement set Fusaka’s activation for 3 December 2025; ethereum.org now records the upgrade as live. The EIP changes the fee adjustment rule—it does not, by itself, prescribe a rollup’s user-facing fee policy.
What the fee floor means for Layer 2 costs
- The blob market still floats. Demand can push the blob base fee above the reserve price; the 1/16 relationship is a lower bound, not a cap.
- The reserve changes with L1 conditions. A higher execution base fee raises the reserve threshold; a lower one reduces it.
- L2 user fees are not set by this EIP. Each rollup’s quote can reflect its own execution costs, data usage, proof costs and pricing policy. Operators may pass data costs through, absorb them or smooth them over time.
- It is not a capacity setting. EIP-7918 changes the blob-fee update logic; the target and maximum blob parameters are configured separately.
For rollup teams, the useful takeaway is to model blob and execution fees separately, then test the effect of the reserve under different L1 base-fee and blob-demand conditions. For users, a claim that EIP-7918 alone guarantees higher or lower L2 fees goes beyond what the EIP specifies.
FAQ
Is the Ethereum blob fee fixed at 1/16 of the L1 base fee?
No. EIP-7918 sets a reserve relationship at the floor. Blob demand can push the actual blob base fee above it, and the threshold changes when the execution base fee changes.
Does EIP-7918 automatically make Layer 2 transactions more expensive?
No automatic retail price follows from the EIP. It adds a reserve to Ethereum’s blob-fee mechanism; each rollup determines how its own costs affect user fees.
When did EIP-7918 go live on Ethereum mainnet?
It was included in the Fusaka upgrade, which activated on 3 December 2025, according to the Ethereum Foundation’s activation announcement and the ethereum.org Fusaka roadmap.
Sources
- EIP-7918: Blob base fee bounded by execution cost — final core specification and rationale.
- EIP-4844: Shard Blob Transactions — blob-gas accounting and the separate fee market.
- Fusaka Mainnet Announcement — Ethereum Foundation — mainnet activation schedule and included EIPs.
- Fusaka — ethereum.org — upgrade overview and live status.
If your team is building a rollup, wallet or Ethereum product and needs help modeling these fee flows in its architecture, talk with SignorCrypto about the technical scope.