Batch costing is applied when a manufacturing facility produces a collection of identical units together in a single production run, rather than tracking individual items or running continuous lines. This lesson outlines how batch costs are calculated and introduces the optimization formula for batch run sizes. 

In a batch costing system, the entire production run is treated as a single job during manufacturing. Costs are accumulated on a batch sheet. Once the batch is completed, the unit cost is determined by dividing the total batch cost by the number of good units produced:

Unit Cost per Batch Item = (Total Batch Material Cost + Total Batch Labor Cost + Applied Overhead + Machine Setup Cost) / Total Number of Good Units Produced

Similar to the inventory EOQ model, batch manufacturing must balance two competing costs: Initial Setup Costs (tooling changes, idle calibration time) and Inventory Holding Costs (storing the finished batch items until the market consumes them).

A medical device plant faces an annual demand (D) of 50,000 units for a specific syringe. The factory’s machines can produce up to 200,000 units per year if run continuously (P). Setting up the production line costs $400 per run (S), and holding a finished syringe in stock for a year costs $2.00 (H).

import math

D = 50000     # Annual Demand
P = 200000    # Annual Production Rate
S = 400       # Setup Cost
H = 2.00      # Holding Cost

# EBQ Formula calculation
ebq = math.sqrt((2 * D * S) / (H * (1 - (D / P))))

print(f"Economic Batch Quantity (EBQ): {ebq:.0f} units per run")

The mathematical computation shows: