diff --git a/frontend/src/lib/recipes/RecipeForm.svelte b/frontend/src/lib/recipes/RecipeForm.svelte
index 2bb39a0..7d7242c 100644
--- a/frontend/src/lib/recipes/RecipeForm.svelte
+++ b/frontend/src/lib/recipes/RecipeForm.svelte
@@ -61,10 +61,19 @@
 	);
 	let steps = $state(initial?.steps.map((s) => s.instruction) ?? ['']);
 	let heroImageUrl = $state<string | null>(initial?.heroImageUrl ?? null);
+	let imageError = $state<string | null>(null);
+
+	const MAX_IMAGE_BYTES = 5 * 1024 * 1024;
 
 	function handleImageChange(e: Event) {
 		const file = (e.currentTarget as HTMLInputElement).files?.[0];
 		if (!file) return;
+		if (file.size > MAX_IMAGE_BYTES) {
+			imageError = 'Datei zu groß. Maximal 5 MB erlaubt.';
+			(e.currentTarget as HTMLInputElement).value = '';
+			return;
+		}
+		imageError = null;
 		const reader = new FileReader();
 		reader.onload = () => {
 			heroImageUrl = reader.result as string;
@@ -196,6 +205,11 @@
 					/>
 					{heroImageUrl ? 'Bild ändern' : 'Bild hochladen'}
 				</label>
+				{#if imageError}
+					<p class="mt-[6px] text-[12px] text-[var(--color-error)]">{imageError}</p>
+				{:else}
+					<p class="mt-[6px] text-[11px] text-[var(--color-text-muted)]">Max. 5 MB</p>
+				{/if}
 				<input type="hidden" name="heroImageUrl" value={heroImageUrl ?? ''} />
 			</div>
 
diff --git a/frontend/src/lib/recipes/RecipeForm.test.ts b/frontend/src/lib/recipes/RecipeForm.test.ts
index 7dcfc6d..b03aa7a 100644
--- a/frontend/src/lib/recipes/RecipeForm.test.ts
+++ b/frontend/src/lib/recipes/RecipeForm.test.ts
@@ -162,4 +162,31 @@ describe('RecipeForm', () => {
 		render(RecipeForm, { props: emptyProps });
 		expect(screen.queryByRole('alert')).not.toBeInTheDocument();
 	});
+
+	it('shows Max. 5 MB hint below upload button', () => {
+		render(RecipeForm, { props: emptyProps });
+		expect(screen.getByText('Max. 5 MB')).toBeInTheDocument();
+	});
+
+	it('shows error when selected file exceeds 5 MB', async () => {
+		const user = userEvent.setup();
+		render(RecipeForm, { props: emptyProps });
+
+		const oversizedFile = new File(['x'.repeat(6 * 1024 * 1024)], 'big.jpg', { type: 'image/jpeg' });
+		const fileInput = document.querySelector('input[type="file"]') as HTMLInputElement;
+		await user.upload(fileInput, oversizedFile);
+
+		expect(screen.getByText(/datei zu groß/i)).toBeInTheDocument();
+	});
+
+	it('does not show file size error for file within 5 MB', async () => {
+		const user = userEvent.setup();
+		render(RecipeForm, { props: emptyProps });
+
+		const okFile = new File(['x'.repeat(1 * 1024 * 1024)], 'small.jpg', { type: 'image/jpeg' });
+		const fileInput = document.querySelector('input[type="file"]') as HTMLInputElement;
+		await user.upload(fileInput, okFile);
+
+		expect(screen.queryByText(/datei zu groß/i)).not.toBeInTheDocument();
+	});
 });