Inventory Management Blog
Expert perspectives on inventory, supply chain and operational excellence to help your business work smarter,
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Forecast Accuracy: How to Measure It and Improve Inventory Planning
Every inventory decision contains an assumption about future demand.
When those assumptions are consistently wrong, the consequences appear as excess stock, stockouts, emergency purchases and unstable replenishment. Forecasting is most useful when it supports timely decisions about purchasing, replenishment and inventory exposure. The objective is not to predict demand perfectly, but to understand uncertainty early enough for the business to respond intelligently.
What is forecast accuracy?
Forecast accuracy measures how closely predicted demand corresponds with actual demand.
The important principle is simple:
Forecast → Actual demand → Variance → Learning → Improved forecast
Yet many businesses create forecasts without systematically measuring how accurate previous forecasts were.
Why forecast error matters
Over-forecasting can result in excess inventory and ageing stock.
Under-forecasting can result in stockouts, lost sales and emergency replenishment.
Both consume working capital and management attention.
Measure accuracy at a useful level
Company-wide forecast accuracy may hide the problems management needs to address.
The purpose is not merely to generate an accuracy percentage. It is to identify where and why forecast error occurs.
Forecasting should be a learning process
A forecast should not disappear after the purchasing decision has been made.
Compare forecast demand with actual demand and investigate significant deviations.
Were they caused by promotions? Seasonality? New products? Customer behaviour? Incorrect assumptions? Supply constraints?
The organisation becomes better at forecasting when it learns systematically from its errors.
Free Inventory Health Check
Assess forecast accuracy along with nine other areas of inventory management with iJCNE’s Free Inventory Health Check.
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