A sales forecast is a projection of future sales levels. A forecast is a less formal version of a sales budget, since the forecast may not have a large amount of supporting detail and also tends to run for just a few months into the future. A forecast is more likely to be based on bottom-up projections from the sales force, based on their expectations of sales to specific customers. A sales budget is more likely to incorporate top-down estimates of sales from the management team.
A sales forecast is used to project resource needs, as well as short-term asset requirements. In particular, a business uses a sales forecast to decide whether its on-hand inventory levels should be ramped up or scaled back.