diff --git a/apps/red-ui/src/app/modules/admin/screens/watermark/watermark-screen/watermark-screen.component.ts b/apps/red-ui/src/app/modules/admin/screens/watermark/watermark-screen/watermark-screen.component.ts
index f3c297204..26ab564a2 100644
--- a/apps/red-ui/src/app/modules/admin/screens/watermark/watermark-screen/watermark-screen.component.ts
+++ b/apps/red-ui/src/app/modules/admin/screens/watermark/watermark-screen/watermark-screen.component.ts
@@ -6,6 +6,7 @@ import {
     AsControl,
     BASE_HREF_FN,
     Debounce,
+    getConfig,
     getCurrentUser,
     getParam,
     IconButtonTypes,
@@ -16,6 +17,7 @@ import {
     trackByFactory,
 } from '@iqser/common-ui';
 import {
+    AppConfig,
     DOSSIER_TEMPLATE_ID,
     type IWatermark,
     type User,
@@ -92,6 +94,7 @@ export class WatermarkScreenComponent implements OnInit {
     readonly #loaded$ = new BehaviorSubject(false);
     readonly #dossierTemplateId = getParam(DOSSIER_TEMPLATE_ID);
     readonly #watermarkId = Number(getParam(WATERMARK_ID));
+    readonly #config = getConfig<AppConfig>();
     #watermark: Partial<IWatermark> = {};
 
     constructor(
@@ -257,11 +260,12 @@ export class WatermarkScreenComponent implements OnInit {
     }
 
     async #loadDocument() {
-        const request = this._http.get('/assets/pdftron/blank.pdf', {
+        const filename = `blank-${this.#config.WATERMARK_PREVIEW_PAPER_FORMAT}.pdf`;
+        const request = this._http.get(`/assets/pdftron/${filename}`, {
             responseType: 'blob',
         });
         const blobData = await firstValueFrom(request);
-        this.instance.UI.loadDocument(blobData, { filename: 'blank.pdf' });
+        this.instance.UI.loadDocument(blobData, { filename });
     }
 
     #disableElements() {
diff --git a/apps/red-ui/src/assets/config/config.json b/apps/red-ui/src/assets/config/config.json
index 59c62b3be..378c6448c 100644
--- a/apps/red-ui/src/assets/config/config.json
+++ b/apps/red-ui/src/assets/config/config.json
@@ -20,5 +20,6 @@
   "BASE_TRANSLATIONS_DIRECTORY": "/assets/i18n/redact/",
   "AVAILABLE_NOTIFICATIONS_DAYS": 30,
   "AVAILABLE_OLD_NOTIFICATIONS_MINUTES": 60,
-  "NOTIFICATIONS_THRESHOLD": 1000
+  "NOTIFICATIONS_THRESHOLD": 1000,
+  "WATERMARK_PREVIEW_PAPER_FORMAT": "a4"
 }
diff --git a/apps/red-ui/src/assets/pdftron/blank.pdf b/apps/red-ui/src/assets/pdftron/blank-a4.pdf
similarity index 100%
rename from apps/red-ui/src/assets/pdftron/blank.pdf
rename to apps/red-ui/src/assets/pdftron/blank-a4.pdf
diff --git a/apps/red-ui/src/assets/pdftron/blank-letter.pdf b/apps/red-ui/src/assets/pdftron/blank-letter.pdf
new file mode 100644
index 000000000..6d678053c
--- /dev/null
+++ b/apps/red-ui/src/assets/pdftron/blank-letter.pdf
@@ -0,0 +1,70 @@
+%PDF-1.4
+%����
+1 0 obj
+<</Creator (Mozilla/5.0 \(Macintosh; Intel Mac OS X 10_15_7\) AppleWebKit/537.36 \(KHTML, like Gecko\) Chrome/114.0.0.0 Safari/537.36)
+/Producer (Skia/PDF m114)
+/CreationDate (D:20230620084257+00'00')
+/ModDate (D:20230620084257+00'00')>>
+endobj
+3 0 obj
+<</ca 1
+/BM /Normal>>
+endobj
+4 0 obj
+<</Filter /FlateDecode
+/Length 139>> stream
+x���1�0EwN�\�Ԇ@�dN� J3�R��K�v�t+
}>bɵ0���3��qz�
+�aՀ��(����>���5{t�Xt�5��Apy�[)ƠV��at�I��NHԉ#X��ڝ�o6և�o���_~e�'��7��4�
+endstream
+endobj
+6 0 obj
+<</Filter /FlateDecode
+/Length 135>> stream
+x��N��0����j�G��:�� �R��K8��ʆ�
>[�;����@��Y�����K��R���Xɴ�lN�d���>�^���u��o��
�	;Yg8N����Sv�������]�F��O���Y���7��:�
+endstream
+endobj
+2 0 obj
+<</Type /Page
+/Resources <</ProcSet [/PDF /Text /ImageB /ImageC /ImageI]
+/ExtGState <</G3 3 0 R>>>>
+/MediaBox [0 0 612 792]
+/Contents 4 0 R
+/StructParents 0
+/Parent 7 0 R>>
+endobj
+5 0 obj
+<</Type /Page
+/Resources <</ProcSet [/PDF /Text /ImageB /ImageC /ImageI]
+/ExtGState <</G3 3 0 R>>>>
+/MediaBox [0 0 792 612]
+/Contents 6 0 R
+/StructParents 1
+/Parent 7 0 R>>
+endobj
+7 0 obj
+<</Type /Pages
+/Count 2
+/Kids [2 0 R 5 0 R]>>
+endobj
+8 0 obj
+<</Type /Catalog
+/Pages 7 0 R>>
+endobj
+xref
+0 9
+0000000000 65535 f 
+0000000015 00000 n 
+0000000719 00000 n 
+0000000268 00000 n 
+0000000305 00000 n 
+0000000907 00000 n 
+0000000514 00000 n 
+0000001095 00000 n 
+0000001156 00000 n 
+trailer
+<</Size 9
+/Root 8 0 R
+/Info 1 0 R>>
+startxref
+1203
+%%EOF
diff --git a/docker/red-ui/docker-entrypoint.sh b/docker/red-ui/docker-entrypoint.sh
index 1f49ec007..bef8197a7 100755
--- a/docker/red-ui/docker-entrypoint.sh
+++ b/docker/red-ui/docker-entrypoint.sh
@@ -23,6 +23,7 @@ AVAILABLE_OLD_NOTIFICATIONS_MINUTES="${AVAILABLE_OLD_NOTIFICATIONS_MINUTES:-60}"
 NOTIFICATIONS_THRESHOLD="${NOTIFICATIONS_THRESHOLD:-1000}"
 BASE_TRANSLATIONS_DIRECTORY="${BASE_TRANSLATIONS_DIRECTORY:-/assets/i18n/redact/}"
 THEME="${THEME:-theme-template}"
+WATERMARK_PREVIEW_PAPER_FORMAT="${WATERMARK_PREVIEW_PAPER_FORMAT:a4}"
 
 
 
@@ -48,7 +49,8 @@ echo '{
           "ANNOTATIONS_THRESHOLD":"'"$ANNOTATIONS_THRESHOLD"'",
           "AVAILABLE_NOTIFICATIONS_DAYS":"'"$AVAILABLE_NOTIFICATIONS_DAYS"'",
           "AVAILABLE_OLD_NOTIFICATIONS_MINUTES":"'"$AVAILABLE_OLD_NOTIFICATIONS_MINUTES"'",
-          "NOTIFICATIONS_THRESHOLD":"'"$NOTIFICATIONS_THRESHOLD"'"
+          "NOTIFICATIONS_THRESHOLD":"'"$NOTIFICATIONS_THRESHOLD"'",
+          "WATERMARK_PREVIEW_PAPER_FORMAT":"'"$WATERMARK_PREVIEW_PAPER_FORMAT"'",
        }' > /usr/share/nginx/html/ui/assets/config/config.json
 
 echo 'Env variables: '
diff --git a/libs/red-domain/src/lib/shared/app-config.ts b/libs/red-domain/src/lib/shared/app-config.ts
index 050a999a0..5b1728a55 100644
--- a/libs/red-domain/src/lib/shared/app-config.ts
+++ b/libs/red-domain/src/lib/shared/app-config.ts
@@ -15,4 +15,5 @@ export interface AppConfig extends IqserAppConfig {
     readonly AVAILABLE_NOTIFICATIONS_DAYS: number;
     readonly AVAILABLE_OLD_NOTIFICATIONS_MINUTES: number;
     readonly NOTIFICATIONS_THRESHOLD: number;
+    readonly WATERMARK_PREVIEW_PAPER_FORMAT: 'a4' | 'letter';
 }