diff --git a/configs/mainnet.yaml b/configs/mainnet.yaml
index 55a973e9a..56f1f8903 100644
--- a/configs/mainnet.yaml
+++ b/configs/mainnet.yaml
@@ -157,6 +157,7 @@ WHISK_PROPOSER_SELECTION_GAP: 2
 
 # EIP7594
 NUMBER_OF_COLUMNS: 128
+MAX_EXTENDED_MATRIX_SIZE: 768
 DATA_COLUMN_SIDECAR_SUBNET_COUNT: 32
 MAX_REQUEST_DATA_COLUMN_SIDECARS: 16384
 
diff --git a/configs/minimal.yaml b/configs/minimal.yaml
index 75e75ce9c..d55e0c398 100644
--- a/configs/minimal.yaml
+++ b/configs/minimal.yaml
@@ -155,6 +155,7 @@ WHISK_PROPOSER_SELECTION_GAP: 1
 
 # EIP7594
 NUMBER_OF_COLUMNS: 128
+MAX_EXTENDED_MATRIX_SIZE: 768
 DATA_COLUMN_SIDECAR_SUBNET_COUNT: 32
 MAX_REQUEST_DATA_COLUMN_SIDECARS: 16384
 
diff --git a/pysetup/spec_builders/eip7594.py b/pysetup/spec_builders/eip7594.py
index 414d73f32..9c5ce4fd9 100644
--- a/pysetup/spec_builders/eip7594.py
+++ b/pysetup/spec_builders/eip7594.py
@@ -19,6 +19,7 @@ from eth2spec.deneb import {preset_name} as deneb
             'FIELD_ELEMENTS_PER_CELL': spec_object.preset_vars['FIELD_ELEMENTS_PER_CELL'].value,
             'FIELD_ELEMENTS_PER_EXT_BLOB': spec_object.preset_vars['FIELD_ELEMENTS_PER_EXT_BLOB'].value,
             'NUMBER_OF_COLUMNS': spec_object.config_vars['NUMBER_OF_COLUMNS'].value,
+            'MAX_EXTENDED_MATRIX_SIZE': spec_object.config_vars['MAX_EXTENDED_MATRIX_SIZE'].value,
         }
 
     @classmethod
diff --git a/specs/_features/eip7594/das-core.md b/specs/_features/eip7594/das-core.md
index 6fee61647..61c79cfd2 100644
--- a/specs/_features/eip7594/das-core.md
+++ b/specs/_features/eip7594/das-core.md
@@ -46,7 +46,7 @@ We define the following Python custom types for type hinting and readability:
 | Name | SSZ equivalent | Description |
 | - | - | - |
 | `DataColumn` | `List[Cell, MAX_BLOB_COMMITMENTS_PER_BLOCK]` | The data of each column in EIP-7594 |
-| `ExtendedMatrix` | `List[Cell, MAX_BLOBS_PER_BLOCK * NUMBER_OF_COLUMNS]` | The full data of one-dimensional erasure coding extended blobs (in row major format) |
+| `ExtendedMatrix` | `List[Cell, MAX_EXTENDED_MATRIX_SIZE]` | The full data of one-dimensional erasure coding extended blobs (in row major format). |
 
 ## Configuration
 
@@ -55,6 +55,7 @@ We define the following Python custom types for type hinting and readability:
 | Name | Value | Description |
 | - | - | - |
 | `NUMBER_OF_COLUMNS` | `uint64(FIELD_ELEMENTS_PER_EXT_BLOB // FIELD_ELEMENTS_PER_CELL)` (= 128) | Number of columns in the extended data matrix. |
+| `MAX_EXTENDED_MATRIX_SIZE` | `uint64(MAX_BLOBS_PER_BLOCK * NUMBER_OF_COLUMNS)` (= 768) | The data size of `ExtendedMatrix`. |
 
 ### Networking
 
diff --git a/tests/core/pyspec/eth2spec/test/eip7594/unittests/test_config_invariants.py b/tests/core/pyspec/eth2spec/test/eip7594/unittests/test_config_invariants.py
index 999bc97b7..e2ec28d74 100644
--- a/tests/core/pyspec/eth2spec/test/eip7594/unittests/test_config_invariants.py
+++ b/tests/core/pyspec/eth2spec/test/eip7594/unittests/test_config_invariants.py
@@ -18,6 +18,7 @@ def test_invariants(spec):
     assert spec.config.MAX_REQUEST_DATA_COLUMN_SIDECARS == (
         spec.config.MAX_REQUEST_BLOCKS_DENEB * spec.config.NUMBER_OF_COLUMNS
     )
+    assert spec.config.MAX_EXTENDED_MATRIX_SIZE == spec.MAX_BLOBS_PER_BLOCK * spec.config.NUMBER_OF_COLUMNS
 
 
 @with_eip7594_and_later