diff --git a/photobooth.py b/photobooth.py
index bbd514c..b31f899 100755
--- a/photobooth.py
+++ b/photobooth.py
@@ -192,6 +192,12 @@ def box_dims_for(term_rows, term_cols, cfg=None):
     if cfg is None or not cfg.real_viewfinder:
         return max_rows, max_cols
     target_cols, target_rows = output_target_dims(cfg, max_cols - 2, max_rows - 2)
+    if cfg.printer_a4 and target_rows is not None:
+        # The printed page is rotated 90 degrees before it reaches the
+        # printer (see prepare_print_frame), so the box shown on screen
+        # should reflect that same landscape swap rather than the
+        # printer's raw portrait character grid.
+        target_cols, target_rows = target_rows, target_cols
     rows = max_rows if target_rows is None else max(min(target_rows + 2, max_rows), 3)
     cols = max(min(target_cols + 2, max_cols), 10)
     return rows, cols