diff --git a/public/js/index.js b/public/js/index.js
index 522f9ac1..2d9fcb1a 100644
--- a/public/js/index.js
+++ b/public/js/index.js
@@ -643,6 +643,7 @@ document.getElementById("addressForm").onsubmit = function (e) {
   const items = cart.map((item) => ({
     id: item.name,
     quantity: item.qty,
+    sellQuantity: getItemSellQuantity(item.name),
   }));
   const request = {
     userId: user.username,
diff --git a/users-api.js b/users-api.js
index f9e3a793..45259faa 100644
--- a/users-api.js
+++ b/users-api.js
@@ -379,7 +379,7 @@ module.exports = function (app, wss, pool) {
         );
         if (!userRow)
           return res.status(404).json({ ok: false, error: "User not found" });
-        if (userRow.balance < price * item.quantity)
+        if (userRow.balance < price * (item.quantity / item.sellQuantity))
           return res.status(400).json({
             ok: false,
             error: `Insufficient balance for item ${item.id}`,