diff --git a/prisma/migrations/20250827234055_files_default_compression_format/migration.sql b/prisma/migrations/20250827234055_files_default_compression_format/migration.sql
new file mode 100644
index 00000000..baffa29d
--- /dev/null
+++ b/prisma/migrations/20250827234055_files_default_compression_format/migration.sql
@@ -0,0 +1,2 @@
+-- AlterTable
+ALTER TABLE "public"."Zipline" ADD COLUMN     "filesDefaultCompressionFormat" TEXT DEFAULT 'jpg';
diff --git a/prisma/schema.prisma b/prisma/schema.prisma
index 1b447125..2e7c1db3 100755
--- a/prisma/schema.prisma
+++ b/prisma/schema.prisma
@@ -42,6 +42,7 @@ model Zipline {
   filesRemoveGpsMetadata              Boolean  @default(false)
   filesRandomWordsNumAdjectives       Int      @default(2)
   filesRandomWordsSeparator           String   @default("-")
+  filesDefaultCompressionFormat       String?  @default("jpg")
 
   urlsRoute  String @default("/go")
   urlsLength Int    @default(6)
diff --git a/src/components/pages/serverSettings/parts/Files.tsx b/src/components/pages/serverSettings/parts/Files.tsx
index 547582ff..a709cf3d 100644
--- a/src/components/pages/serverSettings/parts/Files.tsx
+++ b/src/components/pages/serverSettings/parts/Files.tsx
@@ -35,6 +35,7 @@ export default function Files({
     filesRemoveGpsMetadata: boolean;
     filesRandomWordsNumAdjectives: number;
     filesRandomWordsSeparator: string;
+    filesDefaultCompressionFormat: string;
   }>({
     initialValues: {
       filesRoute: '/u',
@@ -48,6 +49,7 @@ export default function Files({
       filesRemoveGpsMetadata: false,
       filesRandomWordsNumAdjectives: 3,
       filesRandomWordsSeparator: '-',
+      filesDefaultCompressionFormat: 'jpg',
     },
     enhanceGetInputProps: (payload) => ({
       disabled: data?.tampered?.includes(payload.field) || false,
@@ -98,6 +100,7 @@ export default function Files({
       filesRemoveGpsMetadata: data.settings.filesRemoveGpsMetadata ?? false,
       filesRandomWordsNumAdjectives: data.settings.filesRandomWordsNumAdjectives ?? 3,
       filesRandomWordsSeparator: data.settings.filesRandomWordsSeparator ?? '-',
+      filesDefaultCompressionFormat: data.settings.filesDefaultCompressionFormat ?? 'jpg',
     });
   }, [data]);
 
@@ -186,6 +189,19 @@ export default function Files({
             placeholder='-'
             {...form.getInputProps('filesRandomWordsSeparator')}
           />
+
+          <Select
+            label='Default Compression Format'
+            description='The default image compression format to use when only a compression percent is specified.'
+            placeholder='jpg'
+            data={[
+              { value: 'jpg', label: '.jpg' },
+              { value: 'png', label: '.png' },
+              { value: 'webp', label: '.webp' },
+              { value: 'jxl', label: '.jxl' },
+            ]}
+            {...form.getInputProps('filesDefaultCompressionFormat')}
+          />
         </SimpleGrid>
 
         <Button type='submit' mt='md' loading={isLoading} leftSection={<IconDeviceFloppy size='1rem' />}>
diff --git a/src/components/pages/upload/UploadOptionsButton.tsx b/src/components/pages/upload/UploadOptionsButton.tsx
index 367f3948..997fbb61 100755
--- a/src/components/pages/upload/UploadOptionsButton.tsx
+++ b/src/components/pages/upload/UploadOptionsButton.tsx
@@ -199,7 +199,44 @@ export default function UploadOptionsButton({ folder, numFiles }: { folder?: str
             description='The file name format to use when upload this file, the "File name" field will override this value.'
             leftSection={<IconWriting size='1rem' />}
             value={options.format}
-            onChange={(value) => setOption('format', value || ('default' as any))}
+            onChange={(value) => setOption('format', (value as any) || 'default')}
+            comboboxProps={{
+              withinPortal: true,
+              portalProps: {
+                style: {
+                  zIndex: 100000000,
+                },
+              },
+            }}
+          />
+
+          <Select
+            data={[
+              { value: 'default', label: `Default (.${config.files.defaultCompressionFormat ?? 'jpg'})` },
+              { value: 'jpg', label: '.jpg' },
+              { value: 'png', label: '.png' },
+              { value: 'webp', label: '.webp' },
+              { value: 'jxl', label: '.jxl' },
+            ]}
+            label={
+              <>
+                Compression Format{' '}
+                {options.imageCompressionFormat !== 'default' ? (
+                  <Badge variant='outline' size='xs'>
+                    saved
+                  </Badge>
+                ) : null}
+              </>
+            }
+            description={
+              <>
+                The image compression format to use <b>only when a compression percent is specified</b>. Leave
+                at &quot;default&quot; to use the server default compression format.
+              </>
+            }
+            leftSection={<IconFileInfo size='1rem' />}
+            value={options.imageCompressionFormat || 'default'}
+            onChange={(value) => setOption('imageCompressionFormat', (value as any) || 'default')}
             comboboxProps={{
               withinPortal: true,
               portalProps: {
@@ -221,7 +258,7 @@ export default function UploadOptionsButton({ folder, numFiles }: { folder?: str
                 ) : null}
               </>
             }
-            description='The compression level to use on images (only). Leave blank to disable compression.'
+            description='The compression level to use on images (only). The above format will be used to compress images. Leave blank to disable compression.'
             leftSection={<IconPercentage size='1rem' />}
             max={100}
             min={0}
diff --git a/src/lib/config/read/db.ts b/src/lib/config/read/db.ts
index b656080a..f81ef7f6 100644
--- a/src/lib/config/read/db.ts
+++ b/src/lib/config/read/db.ts
@@ -28,6 +28,7 @@ export const DATABASE_TO_PROP = {
   filesRemoveGpsMetadata: 'files.removeGpsMetadata',
   filesRandomWordsNumAdjectives: 'files.randomWordsNumAdjectives',
   filesRandomWordsSeparator: 'files.randomWordsSeparator',
+  filesDefaultCompressionFormat: 'files.defaultCompressionFormat',
 
   urlsRoute: 'urls.route',
   urlsLength: 'urls.length',
diff --git a/src/lib/config/read/env.ts b/src/lib/config/read/env.ts
index 1993210b..4712014f 100644
--- a/src/lib/config/read/env.ts
+++ b/src/lib/config/read/env.ts
@@ -57,6 +57,7 @@ export const ENVS = [
   env('files.removeGpsMetadata', 'FILES_REMOVE_GPS_METADATA', 'boolean', true),
   env('files.randomWordsNumAdjectives', 'FILES_RANDOM_WORDS_NUM_ADJECTIVES', 'number', true),
   env('files.randomWordsSeparator', 'FILES_RANDOM_WORDS_SEPARATOR', 'string', true),
+  env('files.defaultCompressionFormat', 'FILES_DEFAULT_COMPRESSION_FORMAT', 'string', true),
 
   env('urls.route', 'URLS_ROUTE', 'string', true),
   env('urls.length', 'URLS_LENGTH', 'number', true),
diff --git a/src/lib/config/validate.ts b/src/lib/config/validate.ts
index d8b5a234..06a92a40 100755
--- a/src/lib/config/validate.ts
+++ b/src/lib/config/validate.ts
@@ -4,6 +4,7 @@ import { type ZodIssue, z } from 'zod';
 import { log } from '../logger';
 import { ParsedConfig } from './read';
 import { PROP_TO_ENV } from './read/env';
+import { checkOutput, COMPRESS_TYPES } from '../compress';
 
 declare global {
   // eslint-disable-next-line @typescript-eslint/no-namespace
@@ -97,6 +98,10 @@ export const schema = z.object({
     removeGpsMetadata: z.boolean().default(false),
     randomWordsNumAdjectives: z.number().default(3),
     randomWordsSeparator: z.string().default('-'),
+    defaultCompressionFormat: z
+      .enum(COMPRESS_TYPES)
+      .default('jpg')
+      .refine((v) => checkOutput(v), 'System does not support outputting this image format.'),
   }),
   urls: z.object({
     route: z.string().startsWith('/').min(1).trim().toLowerCase().default('/go'),
diff --git a/src/lib/store/uploadOptions.ts b/src/lib/store/uploadOptions.ts
index 810d1534..fd7d3d0c 100755
--- a/src/lib/store/uploadOptions.ts
+++ b/src/lib/store/uploadOptions.ts
@@ -6,6 +6,7 @@ export const defaultUploadOptions: UploadOptionsStore['options'] = {
   deletesAt: 'default',
   format: 'default',
   imageCompressionPercent: null,
+  imageCompressionFormat: 'default',
   maxViews: null,
   addOriginalName: false,
   overrides_returnDomain: null,
@@ -22,6 +23,7 @@ export type UploadOptionsStore = {
     deletesAt: string | 'never';
     format: Config['files']['defaultFormat'] | 'default';
     imageCompressionPercent: number | null;
+    imageCompressionFormat: Config['files']['defaultCompressionFormat'] | 'default';
     maxViews: number | null;
     addOriginalName: boolean | null;
     overrides_returnDomain: string | null;
diff --git a/src/lib/uploader/parseHeaders.ts b/src/lib/uploader/parseHeaders.ts
index 0712f80f..5a08f21f 100755
--- a/src/lib/uploader/parseHeaders.ts
+++ b/src/lib/uploader/parseHeaders.ts
@@ -1,6 +1,7 @@
 import ms from 'ms';
 import { Config } from '../config/validate';
 import { checkOutput, COMPRESS_TYPES, CompressType } from '../compress';
+import { config } from '../config';
 
 // from ms@3.0.0-canary.1
 type Unit =
@@ -148,7 +149,7 @@ function parsePercent(header: keyof UploadHeaders, percent: string) {
 function headerError(header: keyof UploadHeaders, message: string) {
   return {
     header,
-    message: `[${header}]: ${message}`
+    message: `[${header}]: ${message}`,
   };
 }
 
@@ -215,7 +216,7 @@ export function parseHeaders(headers: UploadHeaders, fileConfig: Config['files']
     if (typeof percent === 'object') return percent;
 
     response.imageCompression = {
-      type: 'jpg',
+      type: config.files.defaultCompressionFormat,
       percent,
     };
   }
diff --git a/src/server/routes/api/server/settings/index.ts b/src/server/routes/api/server/settings/index.ts
index 3fe6155f..8c8ce337 100644
--- a/src/server/routes/api/server/settings/index.ts
+++ b/src/server/routes/api/server/settings/index.ts
@@ -1,4 +1,5 @@
 import { bytes } from '@/lib/bytes';
+import { checkOutput, COMPRESS_TYPES } from '@/lib/compress';
 import { reloadSettings } from '@/lib/config';
 import type { readDatabaseSettings } from '@/lib/config/read/db';
 import { safeConfig } from '@/lib/config/safe';
@@ -153,6 +154,9 @@ export default fastifyPlugin(
             filesRemoveGpsMetadata: z.boolean(),
             filesRandomWordsNumAdjectives: z.number().min(1).max(20),
             filesRandomWordsSeparator: z.string(),
+            filesDefaultCompressionFormat: z
+              .enum(COMPRESS_TYPES)
+              .refine((v) => checkOutput(v), 'System does not support outputting this image format.'),
 
             urlsRoute: z
               .string()