diff --git a/app/Services/Quote/FormulaEvaluatorService.php b/app/Services/Quote/FormulaEvaluatorService.php
index 8cf6974..3720f3a 100644
--- a/app/Services/Quote/FormulaEvaluatorService.php
+++ b/app/Services/Quote/FormulaEvaluatorService.php
@@ -1662,11 +1662,11 @@ private function calculateTenantBom(
             $weightFormula = 'AREA × 25';
             $weightCalc = "{$area} × 25";
         } elseif ($productType === 'steel') {
-            // 철재: W1 × (H1 + 550) / 1M, 중량 = 면적 × 25
-            $area = ($W1 * ($H1 + 550)) / 1000000;
+            // 철재: W1 × H1 / 1M, 중량 = 면적 × 25 (레거시 Slat_updateCol12and13 동일)
+            $area = ($W1 * $H1) / 1000000;
             $weight = $area * 25;
-            $areaFormula = '(W1 × (H1 + 550)) / 1,000,000';
-            $areaCalc = "({$W1} × ({$H1} + 550)) / 1,000,000";
+            $areaFormula = '(W1 × H1) / 1,000,000';
+            $areaCalc = "({$W1} × {$H1}) / 1,000,000";
             $weightFormula = 'AREA × 25';
             $weightCalc = "{$area} × 25";
         } else {