diff --git a/packages/server/src/models/ItemEntry.ts b/packages/server/src/models/ItemEntry.ts
index 43b3f9376..0a2aebda0 100644
--- a/packages/server/src/models/ItemEntry.ts
+++ b/packages/server/src/models/ItemEntry.ts
@@ -99,6 +99,13 @@ export default class ItemEntry extends TenantModel {
       : getExlusiveTaxAmount(this.amount, this.taxRate);
   }
 
+  static calcAmount(itemEntry) {
+    const { discount, quantity, rate } = itemEntry;
+    const total = quantity * rate;
+
+    return discount ? total - total * discount * 0.01 : total;
+  }
+
   /**
    * Item entry relations.
    */