diff --git a/colorhash/__main__.py b/colorhash/__main__.py
index 2dac7fe..1c91fa5 100644
--- a/colorhash/__main__.py
+++ b/colorhash/__main__.py
@@ -163,7 +163,8 @@ def main() -> None:
         case "randomart":
             # 17x9 is what openssh uses
             # TODO - allow configuring dimensions, maybe
-            matricizer = RandomartMatricizer(11, 6)
+            w, h = RandomartMatricizer.DIMENSIONS[args.hash]
+            matricizer = RandomartMatricizer(w, h)
         case _:
             assert False, f"invalid args.matrix: {args.matrix}"
 
diff --git a/colorhash/matricizer.py b/colorhash/matricizer.py
index 4e41aa5..6455ff5 100644
--- a/colorhash/matricizer.py
+++ b/colorhash/matricizer.py
@@ -1,6 +1,6 @@
 "All things that turn a hash into a matrix."
 import abc
-from typing import Mapping, Sequence
+from typing import Mapping, Sequence, Self
 
 from .palettes import Palette, DEFAULT_PALETTES, GRADIENT_PALETTES, MULTICOLOR_PALETTES
 
@@ -35,6 +35,16 @@ class Matricizer(metaclass=abc.ABCMeta):
         :returns: the matrix converted from the hash data.
         """
 
+    @staticmethod
+    @abc.abstractmethod
+    def choose_dimensions(hash: str) -> tuple[int, int]:
+        """
+        Choose the dimensions for this matrix based on the hash algorithm.
+
+        :param hash: the hash algorithm being used.
+        :returns: a width and height as a tuple.
+        """
+
     def choose_palette(
         self, data: bytes, palettes: Mapping[str, Palette] | None = None
     ) -> Palette:
@@ -96,6 +106,10 @@ class NibbleMatricizer(Matricizer):
 
         return cols
 
+    @staticmethod
+    def choose_dimensions(hash: str) -> tuple[int, int]:
+        return Self.DIMENSIONS[hash]
+
     def choose_palette(
         self, data: bytes, palettes: Mapping[str, Palette] | None = None
     ) -> Palette:
@@ -110,6 +124,15 @@ class RandomartMatricizer(Matricizer):
     See: https://github.com/openssh/openssh-portable/blob/fc5dc092830de23767c6ef67baa18310a64ee533/sshkey.c#L1014
     """
 
+    DIMENSIONS = {
+        "md5": (7, 6),
+        "sha1": (7, 6),
+        "sha224": (8, 7),
+        "sha256": (8, 7),
+        "sha384": (11, 10),
+        "sha512": (11, 10),
+    }
+
     def matricize(self, data: bytes) -> Matrix:
         """
         Create a matrix based on the "randomart" algorithm from ssh-keygen.
@@ -148,6 +171,10 @@ class RandomartMatricizer(Matricizer):
                     rows[r][c] += 1
         return rows
 
+    @staticmethod
+    def choose_dimensions(hash: str) -> tuple[int, int]:
+        return self.DIMENSIONS[hash]
+
     def choose_palette(
         self, data: bytes, palettes: Mapping[str, Palette] | None = None
     ) -> Palette: