diff --git a/apps/web/src/app/api/worksheets/preview/route.ts b/apps/web/src/app/api/worksheets/preview/route.ts
index 309b4992..b4c41ace 100644
--- a/apps/web/src/app/api/worksheets/preview/route.ts
+++ b/apps/web/src/app/api/worksheets/preview/route.ts
@@ -17,7 +17,14 @@ export async function POST(request: Request) {
       return NextResponse.json({ success: false, error: 'Missing config' }, { status: 400 })
     }
 
-    // Add date and seed if missing
+    // Calculate derived state fields
+    const problemsPerPage = config.problemsPerPage ?? 20
+    const pages = config.pages ?? 1
+    const cols = config.cols ?? 5
+    const rows = Math.ceil((problemsPerPage * pages) / cols)
+    const total = problemsPerPage * pages
+
+    // Add date, seed, and derived fields if missing
     const fullConfig: WorksheetFormState = {
       ...config,
       date:
@@ -28,6 +35,8 @@ export async function POST(request: Request) {
           year: 'numeric',
         }),
       seed: config.seed || Date.now() % 2147483647,
+      rows,
+      total,
     }
 
     // Generate preview
diff --git a/apps/web/src/app/create/worksheets/generatePreview.ts b/apps/web/src/app/create/worksheets/generatePreview.ts
index c6b79963..d059d458 100644
--- a/apps/web/src/app/create/worksheets/generatePreview.ts
+++ b/apps/web/src/app/create/worksheets/generatePreview.ts
@@ -115,7 +115,13 @@ export function generateWorksheetPreview(config: WorksheetFormState): PreviewRes
     }
 
     // Generate Typst sources (one per page)
+    console.log('[generatePreview] Generated problems:', problems.length, 'for config:', {
+      pages: validatedConfig.pages,
+      problemsPerPage: validatedConfig.problemsPerPage,
+      total: validatedConfig.total,
+    })
     const typstSources = generateTypstSource(validatedConfig, problems)
+    console.log('[generatePreview] Generated Typst sources:', typstSources.length, 'pages')
 
     // Compile each page source to SVG (using stdout for single-page output)
     const pages: string[] = []