diff --git a/include/sparsemap.h b/include/sparsemap.h
index 8378690..f3a1ab6 100644
--- a/include/sparsemap.h
+++ b/include/sparsemap.h
@@ -285,6 +285,13 @@ sparsemap_idx_t sparsemap_get_starting_offset(sparsemap_t *map);
  */
 sparsemap_idx_t sparsemap_get_ending_offset(sparsemap_t *map);
 
+/** @brief Returns the percent of bits set in the map.
+ *
+ * @param[in] map The sparsemap reference.
+ * @returns the percent of bits set.
+ */
+double sparsemap_fill_factor(sparsemap_t *map);
+
 /** @brief Provides a method for a callback function to examine every bit set in
  * the index.
  *
diff --git a/src/sparsemap.c b/src/sparsemap.c
index ac11708..44994a2 100644
--- a/src/sparsemap.c
+++ b/src/sparsemap.c
@@ -1183,7 +1183,7 @@ sparsemap_set(sparsemap_t *map, sparsemap_idx_t idx, bool value)
     __sm_append_data(map, &buf[0], sizeof(buf));
 
     uint8_t *p = __sm_get_chunk_data(map, 0);
-    *(sm_idx_t *)p = __sm_get_vector_aligned_offset(idx); // TODO: vector or chunk aligned?
+    *(sm_idx_t *)p = __sm_get_chunk_aligned_offset(idx); // TODO: vector or chunk aligned?
 
     __sm_set_chunk_count(map, 1);
 
@@ -1384,6 +1384,14 @@ sparsemap_get_ending_offset(sparsemap_t *map)
   return offset;
 }
 
+double
+sparsemap_fill_factor(sparsemap_t *map)
+{
+  size_t rank = sparsemap_rank(map, 0, SPARSEMAP_IDX_MAX, true);
+  sparsemap_idx_t end = sparsemap_get_ending_offset(map);
+  return (double)rank / (double)end * 100.0;
+}
+
 void *
 sparsemap_get_data(sparsemap_t *map)
 {