diff --git a/arena.h b/arena.h
index 7ec4c8f..a974ab4 100644
--- a/arena.h
+++ b/arena.h
@@ -347,6 +347,15 @@ void *arena_memcpy(void *dest, const void *src, size_t n)
     return dest;
 }
 
+size_t arena_memory_usage(Arena* arena)
+{
+	size_t mem_usage = 0;
+    for(Region* r = arena->begin; r != NULL; r = r->next) {
+        mem_usage += sizeof(Region) + (sizeof(uintptr_t) * r->capacity);
+    }
+    return mem_usage;
+}
+
 char *arena_strdup(Arena *a, const char *cstr)
 {
     size_t n = arena_strlen(cstr);