diff --git a/packages/matrices/src/m22-m23.ts b/packages/matrices/src/m22-m23.ts
new file mode 100644
index 0000000000..5df4b293eb
--- /dev/null
+++ b/packages/matrices/src/m22-m23.ts
@@ -0,0 +1,16 @@
+import { set4 } from "@thi.ng/vectors3";
+import { MatOpM } from "./api";
+
+/**
+ * Converts M22 to M23 and writes result to `out`.
+ *
+ * @param out
+ * @param m22
+ */
+export const mat22to23: MatOpM =
+    (out, m22) => (
+        !out && (out = []),
+        set4(out, m22),
+        out[4] = out[5] = 0,
+        out
+    );
diff --git a/packages/matrices/src/m23-m22.ts b/packages/matrices/src/m23-m22.ts
new file mode 100644
index 0000000000..16bd1b8285
--- /dev/null
+++ b/packages/matrices/src/m23-m22.ts
@@ -0,0 +1,11 @@
+import { set4 } from "@thi.ng/vectors3";
+import { MatOpM } from "./api";
+
+/**
+ * Converts M23 to M22 and writes result to `out`.
+ *
+ * @param out
+ * @param m23
+ */
+export const mat23to22: MatOpM =
+    (out, m23) => set4(out || [], m23);
diff --git a/packages/matrices/src/m23-m44.ts b/packages/matrices/src/m23-m44.ts
new file mode 100644
index 0000000000..f3e2506fe6
--- /dev/null
+++ b/packages/matrices/src/m23-m44.ts
@@ -0,0 +1,21 @@
+import { MatOpM } from "./api";
+
+/**
+ * Converts M23 to M44 and writes result to `out`.
+ *
+ * @param out
+ * @param m23
+ */
+export const mat23to44: MatOpM =
+    (out, m23) => (
+        !out && (out = []),
+        out[0] = m23[0],
+        out[1] = m23[1],
+        out[4] = m23[2],
+        out[5] = m23[3],
+        out[12] = m23[4],
+        out[13] = m23[5],
+        out[10] = out[15] = 1,
+        out[2] = out[3] = out[6] = out[7] = out[8] = out[9] = out[11] = out[14] = 0,
+        out
+    );