diff --git a/sdk/head/units.h b/sdk/head/units.h
new file mode 100644
index 0000000..1bb4c1a
--- /dev/null
+++ b/sdk/head/units.h
@@ -0,0 +1,26 @@
+/*
+ * Copyright (c) 2026, Chloe M., et al.
+ * Provided under the BSD-3 clause.
+ *
+ * Description: Unit definitions
+ * Author:      Chloe M.
+ */
+
+#ifndef _SDK_UNITS_H_
+#define _SDK_UNITS_H_ 1
+
+/* Storage size units */
+#define UNIT_GIB 0x40000000
+#define UNIT_MIB 0x100000
+
+/* Time units */
+#define UNIT_FS_PER_MS 1000000000000ULL
+#define FSEC_PER_SECOND 1000000000000000ULL
+#define NSEC_PER_SECOND 1000000000ULL
+#define USEC_PER_SECOND 1000000ULL
+#define USEC_PER_MSEC   1000ULL
+
+/* Frequency units */
+#define HZ_PER_MHZ 1000000
+
+#endif  /* !_SDK_UNITS_H_ */