MAPE Calculator
Mean Absolute Percentage Error (MAPE) is a common measure of forecast accuracy, calculated as the average of absolute percentage errors across multiple periods. Lower MAPE indicates better forecasting performance.
Forecast Data (Multiple Periods)
Formula
MAPE = (1/n) × Σ |Actual - Forecast| / Actual × 100%MAPE averages the absolute percentage errors across all periods, providing a single metric to evaluate overall forecast performance.
Variable Definitions
Number of Periods
The number of forecast vs. actual comparisons.
Absolute Percentage Error
Individual period error as a percentage of actual.
Mean Absolute Percentage Error
Average of all APE values.
Example Calculation
Scenario: 4 months of forecast vs. actual data: Period 1: Forecast 100, Actual 110 → APE = 9.09% Period 2: Forecast 120, Actual 115 → APE = 4.35% Period 3: Forecast 90, Actual 95 → APE = 5.26% Period 4: Forecast 130, Actual 125 → APE = 4.00% MAPE = (9.09 + 4.35 + 5.26 + 4.00) / 4 = 5.68%
How to Interpret Your Result
Interpreting MAPE: • <10%: Highly accurate forecasting • 10-20%: Good forecasting • 20-50%: Reasonable forecasting • >50%: Inaccurate forecasting Note: MAPE can be misleading when actual values are near zero.