Definition
A blob fee is a specific metric representing the cost required to include blob data within a blob transaction on a blockchain that supports blobspace. It is distinct from the standard gas fee that applies to execution-related operations and is calculated within a separate fee market designed for high-volume data. The blob fee reflects current demand for blobspace and adjusts dynamically as usage of blob transactions changes. As a result, it serves as a quantitative indicator of the price of temporary data availability for applications that rely heavily on off-execution data storage.
In networks where blob transactions are used, the blob fee is typically expressed as a price per blob or per unit of blob capacity. This metric allows protocols, especially Layer 2 systems that post data to the base layer, to estimate and optimize their data costs independently from computation costs. Because it is segregated from the traditional gas fee, the blob fee helps isolate the economics of data availability from the economics of on-chain execution. Observing blob fee levels over time provides insight into congestion and competition within the dedicated fee market for blobspace.
Context and Usage
The blob fee emerged to support scalable data posting for systems that batch many user operations into a single blob transaction. In this context, the metric captures how expensive it is for such systems to secure data availability on the base chain at any given moment. When demand for blobspace rises, the blob fee increases, signaling tighter capacity and higher costs for data-heavy activity. Conversely, lower blob fees indicate underutilized blobspace and cheaper data posting conditions.
Because blobspace is designed to be used primarily by Layer 2 protocols and other aggregation mechanisms, the blob fee directly influences their operating costs and, indirectly, the fees they charge end users. It coexists with the traditional gas fee, so a single blob transaction may be subject to both execution-related charges and blob-specific pricing. As a metric, the blob fee helps distinguish between pressure on the general gas-based fee market and pressure on the specialized fee market for blobspace, clarifying where congestion is occurring within the system.