Forecast Accuracy Calculator

What is the Acuraccy forecast calculator?

It is a free web error calculator for Demand forecast. It allows us to evaluate the accuracy of a forecasting model with 10 professional metrics based on historical data of real vs. forecast demand.​

Data Entry Modes

The tool offers two methods for entering data:

1. Manual entry: A row-by-row table is completed with 4 fields:
   • Date (optional, free text)
   • SKU (optional, product identifier)
   • Royal (required, actual demand in units)
   • Forecast (required, predicted value)
   • Unlimited rows can be added with the button “+ Add row” and delete individual rows with the trash can icon.
   • There is a button “Clean everything” to reset the table.

1. Upload file: It allows you to load an Excel with the data directly (without the need for manual entry).

Reliability notice: The tool notifies you in real time how many periods you have entered and recommends having at least 12 periods for reliable results.

The 10 metrics it calculates

With each calculation, the tool provides the following indicators, each with its contextual description and a colored traffic light (🟢 green/🟡 yellow/🔴 red):

Visual summary panel

In addition to the detail of each metric, the tool shows a summary panel with:

• El Forecast Accuracy in large number with visual progress bar.

• 6 key metrics on small cards: WMAPE, MAPE, MASE, Bias, Accuracy and Tracking Signal.

• Each value has a colored traffic light depending on its level of performance.

Automatic diagnostics

One of the most relevant functions is the automatic diagnosis that interprets the results without the user needing to know how to read the metrics:

• Compare the MASE against the naive model and issue a verdict:
  • 🔴 ALERT: “Your model is WORSE than simply repeating the sale from the previous period. Review your method.”
  • 🟢 POSITIVE: “Your MASE is 0.23 (<0.8). Your model adds real value vs. a naive forecast. Good work.”

‍