diff --git a/backend/ocr_measurement.py b/backend/ocr_measurement.py
index d00d108..6fddf45 100644
--- a/backend/ocr_measurement.py
+++ b/backend/ocr_measurement.py
@@ -250,6 +250,9 @@ def _calculate_measurements(elements, img_width, img_height):
         'format': _detect_format(img_width, img_height),
     }
 
+    shortest_side = min(img_width, img_height)
+    m['shortest_side'] = shortest_side
+
     headline = elements.get('headline')
     date = elements.get('date')
     legal = elements.get('legal')
@@ -260,10 +263,12 @@ def _calculate_measurements(elements, img_width, img_height):
             'text': headline.get('text', ''),
             'left_margin_px': headline['left'],
             'left_margin_pct': _pct(headline['left'], img_width),
+            'left_margin_shortest_side_pct': _pct(headline['left'], shortest_side),
             'right_margin_px': img_width - headline['right'],
             'right_margin_pct': _pct(img_width - headline['right'], img_width),
             'top_margin_px': headline['top'],
             'top_margin_pct': _pct(headline['top'], img_height),
+            'top_margin_shortest_side_pct': _pct(headline['top'], shortest_side),
             'width_pct': _pct(headline['right'] - headline['left'], img_width),
             'bottom_edge_px': headline['bottom'],
             'bottom_edge_pct': _pct(headline['bottom'], img_height),
@@ -275,6 +280,7 @@ def _calculate_measurements(elements, img_width, img_height):
             'text': date.get('text', ''),
             'left_margin_px': date['left'],
             'left_margin_pct': _pct(date['left'], img_width),
+            'left_margin_shortest_side_pct': _pct(date['left'], shortest_side),
             'top_px': date['top'],
             'top_pct': _pct(date['top'], img_height),
             'char_height_px': date.get('char_height', 0),
@@ -335,18 +341,21 @@ def _calculate_measurements(elements, img_width, img_height):
 
 def _build_measurement_context(measurements):
     """Build formatted text context for injection into QC check prompts."""
+    shortest_side = measurements.get('shortest_side', min(measurements['image_width'], measurements['image_height']))
+
     lines = [
         "=== OCR LAYOUT MEASUREMENTS (computed from pixel-level analysis — NOT visual estimation) ===",
         f"Image: {measurements['image_width']}px x {measurements['image_height']}px ({measurements.get('format', 'unknown')} format)",
+        f"Shortest side: {shortest_side}px (Amazon guideline: margins should be ~7% of shortest side = ~{round(shortest_side * 0.07)}px)",
         "",
     ]
 
     headline = measurements.get('headline')
     if headline:
         lines.append(f"HEADLINE: \"{headline['text']}\"")
-        lines.append(f"  Left margin: {headline['left_margin_px']}px ({headline['left_margin_pct']}% of width)")
+        lines.append(f"  Left margin: {headline['left_margin_px']}px ({headline.get('left_margin_shortest_side_pct', headline['left_margin_pct'])}% of shortest side, {headline['left_margin_pct']}% of width)")
+        lines.append(f"  Top margin: {headline['top_margin_px']}px ({headline.get('top_margin_shortest_side_pct', headline['top_margin_pct'])}% of shortest side)")
         lines.append(f"  Right margin: {headline['right_margin_px']}px ({headline['right_margin_pct']}% of width)")
-        lines.append(f"  Top margin: {headline['top_margin_px']}px ({headline['top_margin_pct']}% of height)")
         lines.append(f"  Headline width: {headline['width_pct']}% of asset width")
         lines.append(f"  Character height: {headline['char_height_px']}px")
         lines.append("")
@@ -354,7 +363,7 @@ def _build_measurement_context(measurements):
     date = measurements.get('date')
     if date:
         lines.append(f"DATE: \"{date['text']}\"")
-        lines.append(f"  Left margin: {date['left_margin_px']}px ({date['left_margin_pct']}% of width)")
+        lines.append(f"  Left margin: {date['left_margin_px']}px ({date.get('left_margin_shortest_side_pct', date['left_margin_pct'])}% of shortest side, {date['left_margin_pct']}% of width)")
         lines.append(f"  Character height: {date['char_height_px']}px")
         lines.append("")