Seasonal Adjustment Calculator

Remove seasonal effects from time-series data by dividing the observed value by its seasonal index.

Seasonally Adjusted Value

120.0000

Seasonal Effect30.0000
Seasonal Effect (%)25.0000

Seasonally Adjusted Value vs Observed Value

Voir la formule →

Formule

## How to Seasonally Adjust Data ### Formula **Adjusted Value = Observed Value / Seasonal Index** Seasonal adjustment removes predictable seasonal patterns from data, revealing the underlying trend. A seasonal index above 1 means the season inflates the value; below 1 means it deflates it. Dividing by the index normalizes the value as if there were no seasonal effect.

Exemple Résolu

December sales are $150 with a seasonal index of 1.25 (holiday boost).

  1. 01Adjusted = 150 / 1.25 = 120
  2. 02Seasonal effect = 150 - 120 = 30
  3. 03The seasonal boost accounts for $30 (25%) of the observed value
  4. 04The underlying (de-seasonalized) value is $120