The simplest formula to use is: sales forecast = the previous period's sales + estimated growth (or shrinkage) in sales for the next period.
How is ecommerce forecasting done? Ecommerce forecasting is done by estimating future demand for your products. These forecasts are typically based on historical metrics like previous sales data and current inventory trends like stock levels.
Top-down sales forecasts Start with the total size of the market and estimate what percentage of the market the business can capture. If the size of a market is $20 million, for example, a company may estimate it can win 10% of that market, making its sales forecast $2 million for the year.
Some business forecasting examples include: determining the feasibility of facing existing competition, measuring the possibility of creating demand for a product, estimating the costs of recurring monthly bills, predicting future sales volumes based on past sales information, efficient allocation of resources, ...