diff --git a/production.py b/production.py
index 0e7cd86..3aab16d 100644
--- a/trytond/trytond/modules/production/production.py
+++ b/trytond/trytond/modules/production/production.py
@@ -10,8 +10,8 @@ from trytond.wizard import Wizard, StateTransition, StateView, Button
 from trytond.pyson import Eval, Bool, If, Id
 from trytond.pool import Pool
 from trytond.transaction import Transaction
-
-from trytond.modules.product import price_digits
+from collections import defaultdict
+from trytond.modules.product import price_digits, round_price
 
 from .exceptions import CostError
 
@@ -487,7 +487,37 @@ class Production(Workflow, ModelSQL, ModelView):
         for production in productions:
             sum_ = Decimal(0)
             prices = {}
+            cost = production.cost
+
+            input_quantities = defaultdict(Decimal)
+            input_costs = defaultdict(Decimal)
+            for input_ in production.inputs:
+                if input_.cost_price is not None:
+                    cost_price = input_.cost_price
+                else:
+                    cost_price = input_.product.cost_price
+                input_quantities[input_.product] += (
+                    Decimal(str(input_.internal_quantity)))
+                input_costs[input_.product] += (
+                    Decimal(str(input_.internal_quantity)) * cost_price)
+            outputs = []
             for output in production.outputs:
+                product = output.product
+                product = output.product
+                if input_quantities.get(output.product):
+                    cost_price = (
+                        input_costs[product] / input_quantities[product])
+                    unit_price = round_price(Uom.compute_price(
+                        product.default_uom, cost_price, output.uom))
+                    if output.unit_price != unit_price:
+                        output.unit_price = unit_price
+                        moves.append(output)
+                    cost -= min(
+                          unit_price * Decimal(str(output.quantity)), cost)
+                else:
+                    outputs.append(output)
+
+            for output in outputs:
                 product = output.product
                 with Transaction().set_context(production._list_price_context):
                     list_price = product.list_price_used
@@ -499,7 +529,7 @@ class Production(Workflow, ModelSQL, ModelView):

             if not sum_ and production.product:
                 prices.clear()
-                for output in production.outputs:
+                for output in outputs:
                     if output.product == production.product:
                         quantity = Uom.compute_qty(
                             output.uom, output.quantity,
@@ -508,14 +538,13 @@ class Production(Workflow, ModelSQL, ModelView):
                         prices[output] = quantity
                         sum_ += quantity

-            for output in production.outputs:
+            for output in outputs:
                 if sum_:
                     ratio = prices.get(output, 0) / sum_
                 else:
-                    ratio = Decimal(1) / len(production.outputs)
+                    ratio = Decimal(1) / len(outputs)
                 quantity = Decimal(str(output.quantity))
-                unit_price = (
-                    production.cost * ratio / quantity).quantize(digits)
+                unit_price = round_price(cost * ratio / quantity)
                 if output.unit_price != unit_price:
                     output.unit_price = unit_price
                     moves.append(output)