diff --git a/subiquity/ui/views/filesystem/partition.py b/subiquity/ui/views/filesystem/partition.py
index cc43ef512..3bf2fe7c4 100644
--- a/subiquity/ui/views/filesystem/partition.py
+++ b/subiquity/ui/views/filesystem/partition.py
@@ -21,6 +21,7 @@
 """
 import logging
 import re
+from typing import Optional
 
 from urwid import connect_signal, Text
 
@@ -91,6 +92,7 @@ def _make_widget(self, form):
 class SizeWidget(StringEditor):
     def __init__(self, form):
         self.form = form
+        self.accurate_value: Optional[int] = None
         super().__init__()
 
     def lost_focus(self):
@@ -112,6 +114,9 @@ def lost_focus(self):
                 ('info_minor',
                  _("Capped partition size at {size}").format(
                      size=self.form.size_str)))
+            # This will invoke self.form.clean_size() and it is expected that
+            # size_str (and therefore self.value) are propertly aligned.
+            self.accurate_value = self.form.size
         else:
             aligned_sz = align_up(sz, self.form.alignment)
             aligned_sz_str = humanize_size(aligned_sz)
@@ -120,6 +125,7 @@ def lost_focus(self):
                 self.form.size.show_extra(
                     ('info_minor', _("Rounded size up to {size}").format(
                         size=aligned_sz_str)))
+            self.accurate_value = aligned_sz
 
 
 class SizeField(FormField):
diff --git a/subiquity/ui/views/filesystem/tests/test_partition.py b/subiquity/ui/views/filesystem/tests/test_partition.py
index cde9fbaaf..acb194b7c 100644
--- a/subiquity/ui/views/filesystem/tests/test_partition.py
+++ b/subiquity/ui/views/filesystem/tests/test_partition.py
@@ -9,6 +9,7 @@
 from subiquity.client.controllers.filesystem import FilesystemController
 from subiquity.common.filesystem import gaps
 from subiquity.models.filesystem import (
+    MiB,
     dehumanize_size,
     )
 from subiquity.models.tests.test_filesystem import (
@@ -64,6 +65,7 @@ def test_create_partition(self):
         gap = gaps.Gap(device=disk, offset=1 << 20, size=99 << 30)
         view, stretchy = make_partition_view(model, disk, gap=gap)
         view_helpers.enter_data(stretchy.form, valid_data)
+        stretchy.form.size.widget.lost_focus()
         view_helpers.click(stretchy.form.done_btn.base_widget)
         valid_data['mount'] = '/'
         valid_data['size'] = dehumanize_size(valid_data['size'])
@@ -82,6 +84,7 @@ def test_edit_partition(self):
         view, stretchy = make_partition_view(model, disk, partition=partition)
         self.assertTrue(stretchy.form.done_btn.enabled)
         view_helpers.enter_data(stretchy.form, form_data)
+        stretchy.form.size.widget.lost_focus()
         view_helpers.click(stretchy.form.done_btn.base_widget)
         expected_data = {
             'size': dehumanize_size(form_data['size']),
@@ -117,6 +120,7 @@ def test_edit_existing_partition(self):
         self.assertFalse(stretchy.form.size.enabled)
         self.assertTrue(stretchy.form.done_btn.enabled)
         view_helpers.enter_data(stretchy.form, form_data)
+        stretchy.form.size.widget.lost_focus()
         view_helpers.click(stretchy.form.done_btn.base_widget)
         expected_data = {
             'fstype': 'xfs',
@@ -184,6 +188,7 @@ def test_edit_boot_partition(self):
         self.assertEqual(stretchy.form.mount.value, "/boot/efi")
 
         view_helpers.enter_data(stretchy.form, form_data)
+        stretchy.form.size.widget.lost_focus()
         view_helpers.click(stretchy.form.done_btn.base_widget)
         expected_data = {
             'size': dehumanize_size(form_data['size']),
@@ -252,3 +257,26 @@ def test_format_entire_unusual_filesystem(self):
         view, stretchy = make_format_entire_view(model, disk)
         self.assertEqual(
             stretchy.form.fstype.value, None)
+
+    def test_create_partition_unaligned_size(self):
+        # In LP: #2013201, the user would type in 1.1G and the partition
+        # created would not be aligned to a MiB boundary.
+        unaligned_data = {
+            'size': '1.1G',  # Corresponds to 1181116006.4 bytes (not an int)
+            'fstype': 'ext4',
+        }
+        valid_data = {
+            'mount': '/',
+            'size': 1127 * MiB,  # ~1.10058 GiB
+            'use_swap': False,
+            'fstype': 'ext4',
+        }
+        model, disk = make_model_and_disk()
+        gap = gaps.Gap(device=disk, offset=1 << 20, size=99 << 30)
+        view, stretchy = make_partition_view(model, disk, gap=gap)
+        view_helpers.enter_data(stretchy.form, unaligned_data)
+        stretchy.form.size.widget.lost_focus()
+        view_helpers.click(stretchy.form.done_btn.base_widget)
+        view.controller.partition_disk_handler.assert_called_once_with(
+            stretchy.disk, valid_data, partition=None, gap=gap
+        )
diff --git a/subiquitycore/ui/form.py b/subiquitycore/ui/form.py
index 3adaf258f..43cf51cf2 100644
--- a/subiquitycore/ui/form.py
+++ b/subiquitycore/ui/form.py
@@ -554,7 +554,11 @@ def as_data(self):
         data = {}
         for field in self._fields:
             if field.enabled:
-                data[field.field.name] = field.value
+                accurate_value = getattr(field.widget, "accurate_value", None)
+                if accurate_value is not None:
+                    data[field.field.name] = accurate_value
+                else:
+                    data[field.field.name] = field.value
         return data