diff --git a/include/sys/arch_interface.h b/include/sys/arch_interface.h
index c9e99ec94ba..b27aeb94d37 100644
--- a/include/sys/arch_interface.h
+++ b/include/sys/arch_interface.h
@@ -126,6 +126,29 @@ static inline uint32_t arch_k_cycle_get_32(void);
  *
  * @see Z_THREAD_STACK_OBJ_ALIGN
  */
+
+/**
+ * @def ARCH_THREAD_STACK_SIZE_ADJUST(size)
+ * @brief Round up a stack buffer size to alignment constraints
+ *
+ * Adjust a requested stack buffer size to the true size of its underlying
+ * buffer, defined as the area usable for thread stack context and thread-
+ * local storage.
+ *
+ * The size value passed here does not include storage reserved for platform
+ * data.
+ *
+ * The returned value is either the same size provided (if already properly
+ * aligned), or rounded up to satisfy alignment constraints.  Calculations
+ * performed here *must* be idempotent.
+ *
+ * Optional definition. If undefined, stack buffer sizes are either:
+ * - Rounded up to the next power of two if user mode is enabled on an arch
+ *   with an MPU that requires such alignment
+ * - Rounded up to ARCH_STACK_PTR_ALIGN
+ *
+ * @see Z_THREAD_STACK_SIZE_ADJUST
+ */
 /** @} */
 
 /**
diff --git a/include/sys/thread_stack.h b/include/sys/thread_stack.h
index a1b70de846c..ff60153d07c 100644
--- a/include/sys/thread_stack.h
+++ b/include/sys/thread_stack.h
@@ -113,6 +113,41 @@ static inline char *z_stack_ptr_align(char *ptr)
 #define Z_THREAD_STACK_OBJ_ALIGN(size)	ARCH_STACK_PTR_ALIGN
 #endif /* ARCH_THREAD_STACK_OBJ_ALIGN */
 
+/**
+ * @def Z_THREAD_STACK_SIZE_ADJUST
+ * @brief Round up a requested stack size to satisfy constraints
+ *
+ * Given a requested stack buffer size, return an adjusted size value for
+ * the entire stack object which takes into consideration:
+ *
+ * - Reserved memory for platform data
+ * - Alignment of stack buffer bounds to CPU/ABI constraints
+ * - Alignment of stack buffer bounds to satisfy memory management hardware
+ *   constraints such that a protection region can cover the stack buffer area
+ *
+ * If CONFIG_USERSPACE is enabled, this determines the size of stack objects
+ * which  may be used by user mode threads, or threads running in supervisor
+ * mode which may later drop privileges to user mode.
+ *
+ * Arches define this with ARCH_THREAD_STACK_SIZE_ADJUST().
+ *
+ * If ARCH_THREAD_STACK_SIZE_ADJUST is not defined, assume rounding up to
+ * ARCH_STACK_PTR_ALIGN is appropriate.
+ *
+ * Any memory reserved for platform data is also included in the total
+ * returned.
+ *
+ * @param size Requested size of the stack buffer
+ * @return Adjusted size of the stack object
+ */
+#if defined(ARCH_THREAD_STACK_SIZE_ADJUST)
+#define Z_THREAD_STACK_SIZE_ADJUST(size) \
+	(ARCH_THREAD_STACK_SIZE_ADJUST(size) + K_THREAD_STACK_RESERVED)
+#else
+#define Z_THREAD_STACK_SIZE_ADJUST(size) \
+	(ROUND_UP((size), ARCH_STACK_PTR_ALIGN) + K_THREAD_STACK_RESERVED)
+#endif /* ARCH_THREAD_STACK_SIZE_ADJUST */
+
 /**
  * @brief Obtain an extern reference to a stack
  *