diff --git a/libraries/AP_HAL/AP_HAL_Boards.h b/libraries/AP_HAL/AP_HAL_Boards.h
index a1973ad7ce..9d140044b4 100644
--- a/libraries/AP_HAL/AP_HAL_Boards.h
+++ b/libraries/AP_HAL/AP_HAL_Boards.h
@@ -92,13 +92,27 @@
 /* CPU classes, used to select if CPU intensive algorithms should be used
  * Note that these are only approximate, not exact CPU speeds. */
 
-/* 150Mhz: PX4 or similar. Assumes:
+/* 150Mhz: STM32F4 or similar. Assumes:
  *  - hardware floating point
- *  - tens of kilobytes of memory available */
+ *  - tens of kilobytes of memory available
+*/
 #define HAL_CPU_CLASS_150  3
+
 /* GigaHz class: SITL, BeagleBone etc. Assumes megabytes of memory available. */
 #define HAL_CPU_CLASS_1000 4
 
+
+/*
+  memory classes, in kbytes. Board must have at least the given amount
+  of memory
+*/
+#define HAL_MEM_CLASS_20   1
+#define HAL_MEM_CLASS_64   2
+#define HAL_MEM_CLASS_192  3
+#define HAL_MEM_CLASS_300  4
+#define HAL_MEM_CLASS_500  5
+#define HAL_MEM_CLASS_1000 6
+
 /* Operating system features
  *
  * HAL implementations may define the following extra feature defines to 1 if
diff --git a/libraries/AP_HAL/board/chibios.h b/libraries/AP_HAL/board/chibios.h
index ab6cbce84c..305da45355 100644
--- a/libraries/AP_HAL/board/chibios.h
+++ b/libraries/AP_HAL/board/chibios.h
@@ -4,7 +4,20 @@
 #include <hal.h>
 
 #define HAL_BOARD_NAME "ChibiOS"
-#define HAL_CPU_CLASS HAL_CPU_CLASS_150
+
+#if HAL_MEMORY_TOTAL_KB >= 1000
+#define HAL_MEM_CLASS HAL_MEM_CLASS_1000
+#elif HAL_MEMORY_TOTAL_KB >= 500
+#define HAL_MEM_CLASS HAL_MEM_CLASS_500
+#elif HAL_MEMORY_TOTAL_KB >= 300
+#define HAL_MEM_CLASS HAL_MEM_CLASS_300
+#elif HAL_MEMORY_TOTAL_KB >= 192
+#define HAL_MEM_CLASS HAL_MEM_CLASS_192
+#elif HAL_MEMORY_TOTAL_KB >= 64
+#define HAL_MEM_CLASS HAL_MEM_CLASS_64
+#else
+#define HAL_MEM_CLASS HAL_MEM_CLASS_20
+#endif
 
 #ifndef HAL_GPIO_LED_ON
 #define HAL_GPIO_LED_ON           0
diff --git a/libraries/AP_HAL/board/empty.h b/libraries/AP_HAL/board/empty.h
index c2d9c3d370..bc2b680d3e 100644
--- a/libraries/AP_HAL/board/empty.h
+++ b/libraries/AP_HAL/board/empty.h
@@ -2,6 +2,7 @@
 
 #define HAL_BOARD_NAME "EMPTY"
 #define HAL_CPU_CLASS HAL_CPU_CLASS_150
+#define HAL_MEM_CLASS HAL_MEM_CLASS_192
 #define HAL_STORAGE_SIZE            16384
 #define HAL_STORAGE_SIZE_AVAILABLE  HAL_STORAGE_SIZE
 #define HAL_INS_DEFAULT HAL_INS_HIL
diff --git a/libraries/AP_HAL/board/linux.h b/libraries/AP_HAL/board/linux.h
index e4a8b87bc2..0f25f9a333 100644
--- a/libraries/AP_HAL/board/linux.h
+++ b/libraries/AP_HAL/board/linux.h
@@ -2,6 +2,7 @@
 
 #define HAL_BOARD_NAME "Linux"
 #define HAL_CPU_CLASS HAL_CPU_CLASS_1000
+#define HAL_MEM_CLASS HAL_MEM_CLASS_1000
 #define HAL_OS_POSIX_IO 1
 #define HAL_OS_SOCKETS 1
 #define HAL_STORAGE_SIZE            16384
diff --git a/libraries/AP_HAL/board/sitl.h b/libraries/AP_HAL/board/sitl.h
index 04014851e9..39f873668d 100644
--- a/libraries/AP_HAL/board/sitl.h
+++ b/libraries/AP_HAL/board/sitl.h
@@ -2,6 +2,7 @@
 
 #define HAL_BOARD_NAME "SITL"
 #define HAL_CPU_CLASS HAL_CPU_CLASS_1000
+#define HAL_MEM_CLASS HAL_MEM_CLASS_1000
 #define HAL_OS_POSIX_IO 1
 #define HAL_OS_SOCKETS 1
 #define HAL_STORAGE_SIZE            16384