calculateFree Online Forecast Accuracy Calculator

This web page offers the same basic accuracy calculations as our Prophecy demand forecasting software.

You can use this page to calculate your forecasting accuracy by item and with all the summary measures described in our knowledgbase article, "5 Forecast Accuracy Formulae".

Privacy Note:
This page runs entirely with client-side javascript. The forecast versus actual data you supply stays on your computer and is NOT transmitted back across the internet.


  1. Enter a list if items, forecasts and actuals into the text area below, load from Excel or paste them in from the clipboard.  For Excel the data must be on the first 'tab' and the file format must be ".xlsx" (Open Office XML / Excel 2007 or later).
    Here is a small example, using commas as the delimiter, though semi-colons, tabs or pipe characters ('|') will work too.  Your data can have an optional header row.  Field 1 is the item description, field 2 is the forecast and field 3 is the actual sale:
    Item 1,350,411
    Item 1,200,192
    Item 1,500,454
  2. Alter the accuracy band parameters in the panel below, if required.
  3. Click the Submit button and view the results.
  4. Sort the details view in ascending or descending order by clicking any of the header cells.  Shift+click will sort on absolute values (i.e. ignoring the sign).

Accuracy Bands

# Percent