diff --git a/diskimage_builder/lib/disk-image-create b/diskimage_builder/lib/disk-image-create
index cfd7cf40..7dd03909 100644
--- a/diskimage_builder/lib/disk-image-create
+++ b/diskimage_builder/lib/disk-image-create
@@ -381,8 +381,8 @@ else
     sudo du -a -c -x ${TMP_BUILD_DIR}/built > ${du_output}
     # the last line is the total size from "-c".
     if [ -n "$DIB_IMAGE_EXTRA_SIZE" ]; then
-        # add DIB_IMAGE_EXTRA_SIZE to create a bigger image as requested
-        du_extra_size=$(echo "$DIB_IMAGE_EXTRA_SIZE" | awk '{printf("%d\n",$1 * 1024 *1024)}')
+        # add DIB_IMAGE_EXTRA_SIZE megabytes to create a bigger image as requested
+        du_extra_size=$(echo "$DIB_IMAGE_EXTRA_SIZE" | awk '{printf("%d\n",$1 * 1024)}')
         du_size_tmp=$(tail -n1 ${du_output} | cut -f1)
         du_size=$(echo "$du_size_tmp $du_extra_size" | awk '{print int($1 + $2)}')
     else
diff --git a/doc/source/user_guide/building_an_image.rst b/doc/source/user_guide/building_an_image.rst
index b724e1b2..14aaee9e 100644
--- a/doc/source/user_guide/building_an_image.rst
+++ b/doc/source/user_guide/building_an_image.rst
@@ -627,7 +627,7 @@ following arguments:
 
 ``--image-extra-size``
    Extra space to add when automatically calculating image size, in
-   gigabytes.  This overrides the default 60% scale up as described
+   megabytes.  This overrides the default 60% scale up as described
    above for ``--image-size``.  Can also set ``DIB_IMAGE_EXTRA_SIZE``.
 
 The special node named ``mkfs_root`` is affected by the following;
diff --git a/releasenotes/notes/image-size-padding-mb-574104d40fdd2345.yaml b/releasenotes/notes/image-size-padding-mb-574104d40fdd2345.yaml
new file mode 100644
index 00000000..5eafd65e
--- /dev/null
+++ b/releasenotes/notes/image-size-padding-mb-574104d40fdd2345.yaml
@@ -0,0 +1,5 @@
+---
+upgrade:
+  - |
+    The ``--image-extra-size`` argument has changed from gigabytes to
+    megabytes to make it more practical for use on smaller images.