Calculate MAPE and understand its limitations near zero.
MAPE is scale-free and intuitive but breaks down when actuals approach zero, since dividing by a tiny number produces enormous percentages. Weighted MAPE avoids that by working on totals. For intermittent demand with many zero periods, MAPE is unusable and weighted forms or absolute measures should be used instead.
Mean Absolute Percentage Error
MAPE = Σ|actual − forecast| ÷ |actual| ÷ n × 100
MAPE = Σ|actual − forecast| ÷ |actual| ÷ n × 100 MAPE is scale-free and intuitive but breaks down when actuals approach zero, since dividing by a tiny number produces enormous percentages. Weighted MAPE avoids that by working on totals.
For intermittent demand with many zero periods, MAPE is unusable and weighted forms or absolute measures should be used instead.
This calculator takes 4 inputs: Sum of absolute percentage errors, Number of periods, Total actual value, Total forecast value. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.