diff --git a/erpnext/manufacturing/doctype/production_plan/services/reservation.py b/erpnext/manufacturing/doctype/production_plan/services/reservation.py
index ee2a1bceb34..615c8b179f3 100644
--- a/erpnext/manufacturing/doctype/production_plan/services/reservation.py
+++ b/erpnext/manufacturing/doctype/production_plan/services/reservation.py
@@ -3,7 +3,6 @@
 
 """Stock reservation for Production Plan (extracted from production_plan.py)."""
 
-
 import frappe
 from frappe import _
 from frappe.model.document import Document
@@ -48,15 +47,11 @@ def get_reserved_qty_for_production_plan(item_code, warehouse):
 def _production_plan_reserved_qty(item_code, warehouse, non_completed_production_plans):
 	table = frappe.qb.DocType("Production Plan")
 	child = frappe.qb.DocType("Material Request Plan Item")
-	qty = (
-		Case().when(child.quantity == 0, child.required_bom_qty).else_(child.quantity)
-		* child.conversion_factor
-	)
 	query = (
 		frappe.qb.from_(table)
 		.inner_join(child)
 		.on(table.name == child.parent)
-		.select(Sum(qty))
+		.select(Sum(child.required_bom_qty))
 		.where(_plan_reserved_filter(table, child, item_code, warehouse))
 	)
 	if non_completed_production_plans:
diff --git a/erpnext/manufacturing/doctype/production_plan/test_production_plan.py b/erpnext/manufacturing/doctype/production_plan/test_production_plan.py
index 97d286e429d..d414755abd0 100644
--- a/erpnext/manufacturing/doctype/production_plan/test_production_plan.py
+++ b/erpnext/manufacturing/doctype/production_plan/test_production_plan.py
@@ -1559,6 +1559,33 @@ class TestProductionPlan(ERPNextTestSuite):
 		reserved_qty_after_mr = flt(frappe.db.get_value("Bin", bin_name, "reserved_qty_for_production_plan"))
 		self.assertEqual(reserved_qty_after_mr, before_qty)
 
+	def test_reserved_qty_for_production_plan_with_partial_stock(self):
+		from erpnext.stock.utils import get_or_make_bin
+
+		fg_item = make_item(properties={"is_stock_item": 1}).name
+		rm_item = make_item(properties={"is_stock_item": 1}).name
+		make_bom(item=fg_item, raw_materials=[rm_item], source_warehouse="_Test Warehouse - _TC")
+
+		make_stock_entry(item_code=rm_item, qty=4, rate=100, target="_Test Warehouse - _TC")
+
+		bin_name = get_or_make_bin(rm_item, "_Test Warehouse - _TC")
+		before_qty = flt(frappe.db.get_value("Bin", bin_name, "reserved_qty_for_production_plan"))
+
+		pln = create_production_plan(item_code=fg_item, planned_qty=10, ignore_existing_ordered_qty=1)
+
+		row = next(d for d in pln.mr_items if d.item_code == rm_item)
+		self.assertEqual(row.required_bom_qty, 10)
+		self.assertEqual(row.quantity, 6)
+
+		after_qty = flt(frappe.db.get_value("Bin", bin_name, "reserved_qty_for_production_plan"))
+		self.assertEqual(after_qty - before_qty, 10)
+
+		pln.reload()
+		pln.cancel()
+
+		after_cancel = flt(frappe.db.get_value("Bin", bin_name, "reserved_qty_for_production_plan"))
+		self.assertEqual(after_cancel, before_qty)
+
 	def test_from_warehouse_for_purchase_material_request(self):
 		from erpnext.stock.doctype.warehouse.test_warehouse import create_warehouse
 		from erpnext.stock.utils import get_or_make_bin
diff --git a/erpnext/patches.txt b/erpnext/patches.txt
index 419a42e0b52..4bc36ce882e 100644
--- a/erpnext/patches.txt
+++ b/erpnext/patches.txt
@@ -501,3 +501,4 @@ erpnext.patches.v16_0.crm_settings_handle_allowed_users_for_frappe_crm
 erpnext.patches.v16_0.access_control_for_project_users
 erpnext.patches.v16_0.enable_book_stock_expense_gl_entries
 execute:frappe.db.set_single_value("Stock Settings", "use_inline_serial_batch_editor", 0)
+erpnext.patches.v16_0.recompute_production_plan_reserved_qty
diff --git a/erpnext/patches/v16_0/recompute_production_plan_reserved_qty.py b/erpnext/patches/v16_0/recompute_production_plan_reserved_qty.py
new file mode 100644
index 00000000000..c33d59eea8f
--- /dev/null
+++ b/erpnext/patches/v16_0/recompute_production_plan_reserved_qty.py
@@ -0,0 +1,23 @@
+import frappe
+
+
+def execute():
+	plans = frappe.get_all(
+		"Production Plan",
+		filters={"docstatus": 1, "status": ("not in", ["Completed", "Closed"])},
+		pluck="name",
+	)
+	if not plans:
+		return
+
+	rows = frappe.get_all(
+		"Material Request Plan Item",
+		filters={"parent": ("in", plans)},
+		fields=["item_code", "warehouse"],
+	)
+
+	for item_code, warehouse in {(row.item_code, row.warehouse) for row in rows}:
+		bin_name = frappe.db.get_value("Bin", {"item_code": item_code, "warehouse": warehouse})
+		if not bin_name:
+			continue
+		frappe.get_doc("Bin", bin_name, for_update=True).update_reserved_qty_for_production_plan()