diff --git a/grub-core/fs/btrfs.c b/grub-core/fs/btrfs.c
index ba3ea96a1..937153306 100644
--- a/grub-core/fs/btrfs.c
+++ b/grub-core/fs/btrfs.c
@@ -2189,6 +2189,33 @@ grub_btrfs_label (grub_device_t device, char **label)
 }
 
 #ifdef GRUB_UTIL
+
+struct embed_region {
+  unsigned int start;
+  unsigned int secs;
+};
+
+/*
+ * https://btrfs.wiki.kernel.org/index.php/Manpage/btrfs(5)#BOOTLOADER_SUPPORT
+ * The first 1 MiB on each device is unused with the exception of primary
+ * superblock that is on the offset 64 KiB and spans 4 KiB.
+ */
+
+static const struct {
+  struct embed_region available;
+  struct embed_region used[6];
+} btrfs_head = {
+  .available = {0, GRUB_DISK_KiB_TO_SECTORS (1024)}, /* The first 1 MiB. */
+  .used = {
+    {0, 1},                                                        /* boot.S. */
+    {GRUB_DISK_KiB_TO_SECTORS (64) - 1, 1},                        /* Overflow guard. */
+    {GRUB_DISK_KiB_TO_SECTORS (64), GRUB_DISK_KiB_TO_SECTORS (4)}, /* 4 KiB superblock. */
+    {GRUB_DISK_KiB_TO_SECTORS (68), 1},                            /* Overflow guard. */
+    {GRUB_DISK_KiB_TO_SECTORS (1024) - 1, 1},                      /* Overflow guard. */
+    {0, 0}                                                         /* Array terminator. */
+  }
+};
+
 static grub_err_t
 grub_btrfs_embed (grub_device_t device __attribute__ ((unused)),
 		  unsigned int *nsectors,
@@ -2196,25 +2223,62 @@ grub_btrfs_embed (grub_device_t device __attribute__ ((unused)),
 		  grub_embed_type_t embed_type,
 		  grub_disk_addr_t **sectors)
 {
-  unsigned i;
+  unsigned int i, j, n = 0;
+  const struct embed_region *u;
+  grub_disk_addr_t *map;
 
   if (embed_type != GRUB_EMBED_PCBIOS)
     return grub_error (GRUB_ERR_NOT_IMPLEMENTED_YET,
 		       "BtrFS currently supports only PC-BIOS embedding");
 
-  if (64 * 2 - 1 < *nsectors)
-    return grub_error (GRUB_ERR_OUT_OF_RANGE,
-		       N_("your core.img is unusually large.  "
-			  "It won't fit in the embedding area"));
-
-  *nsectors = 64 * 2 - 1;
-  if (*nsectors > max_nsectors)
-    *nsectors = max_nsectors;
-  *sectors = grub_calloc (*nsectors, sizeof (**sectors));
-  if (!*sectors)
+  map = grub_calloc (btrfs_head.available.secs, sizeof (*map));
+  if (map == NULL)
     return grub_errno;
-  for (i = 0; i < *nsectors; i++)
-    (*sectors)[i] = i + 1;
+
+  /*
+   * Populating the map array so that it can be used to index if a disk
+   * address is available to embed:
+   *   - 0: available,
+   *   - 1: unavailable.
+   */
+  for (u = btrfs_head.used; u->secs; ++u)
+    {
+      unsigned int end = u->start + u->secs;
+
+      if (end > btrfs_head.available.secs)
+        end = btrfs_head.available.secs;
+      for (i = u->start; i < end; ++i)
+        map[i] = 1;
+    }
+
+  /* Adding up n until it matches total size of available embedding area. */
+  for (i = 0; i < btrfs_head.available.secs; ++i)
+    if (map[i] == 0)
+      n++;
+
+  if (n < *nsectors)
+    {
+      grub_free (map);
+      return grub_error (GRUB_ERR_OUT_OF_RANGE,
+		         N_("your core.img is unusually large.  "
+			    "It won't fit in the embedding area"));
+    }
+
+  if (n > max_nsectors)
+    n = max_nsectors;
+
+  /*
+   * Populating the array so that it can used to index disk block address for
+   * an image file's offset to be embedded on disk (the unit is in sectors):
+   *   - i: The disk block address relative to btrfs_head.available.start,
+   *   - j: The offset in image file.
+   */
+  for (i = 0, j = 0; i < btrfs_head.available.secs && j < n; ++i)
+    if (map[i] == 0)
+      map[j++] = btrfs_head.available.start + i;
+
+  *nsectors = n;
+  *sectors = map;
 
   return GRUB_ERR_NONE;
 }
diff --git a/include/grub/disk.h b/include/grub/disk.h
index f95aca929..06210a704 100644
--- a/include/grub/disk.h
+++ b/include/grub/disk.h
@@ -182,6 +182,8 @@ typedef struct grub_disk_memberlist *grub_disk_memberlist_t;
 /* Return value of grub_disk_native_sectors() in case disk size is unknown. */
 #define GRUB_DISK_SIZE_UNKNOWN	 0xffffffffffffffffULL
 
+#define GRUB_DISK_KiB_TO_SECTORS(x) ((x) << (10 - GRUB_DISK_SECTOR_BITS))
+
 /* Convert sector number from one sector size to another. */
 static inline grub_disk_addr_t
 grub_convert_sector (grub_disk_addr_t sector,