How is seasonality calculated?

Seasonal trends are automatically detected by StockTrim and applied to your forecasts. The system looks at your last 24 months of sales history and calculates a factor for every month based on the difference (increase/decrease) in sales of the month compared with the historical average, then applies this factor to future months.

You can disable seasonality for an item by bringing up the demand analysis and disabling the "apply seasonality" setting.