How to Calculate SMAPE in Excel (With Examples)


The symmetric mean absolute percentage error (SMAPE) is used to measure the predictive accuracy of models. It is calculated as:

SMAPE = (1/n) * Σ(|forecast – actual| / ((|actual| + |forecast|)/2) * 100

where:

  • Σ – a symbol that means “sum”
  • n – sample size
  • actual – the actual data value
  • forecast – the forecasted data value

The smaller the value for SMAPE, the better the predictive accuracy of a given model.

The following step-by-step example explains how to calculate SMAPE in Excel.

Step 1: Enter the Data

First, we’ll enter some fake data for the actual sales and the forecasted sales during 12 consecutive sales periods for some company:

Step 2: Calculate the SMAPE Differences

Next, we’ll calculate the SMAPE difference for each sales period using the following formula:

Step 3: Calculate SMAPE

Lastly, we’ll use the following formula to calculate SMAPE:

SMAPE in Excel

The SMAPE for this particular model turns out to be 9.89%.

Additional Resources

How to Calculate MAPE in Excel
How to Calculate MAE in Excel
How to Calculate RMSE in Excel

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