Why Forecasting Matters
A sales forecast is your best prediction of future revenue. It drives decisions about hiring, inventory, marketing spend, and cash flow management. An inaccurate forecast leads to either overinvesting in resources you do not need or being unprepared for demand you did not anticipate.
Bottom Up vs Top Down
Top down forecasting starts with the total market and estimates your share. It is useful for new products but tends to be overly optimistic. Bottom up forecasting builds from your actual pipeline, conversion rates, and sales capacity. It is more grounded in reality and should be your primary approach.
The Pipeline Method
Multiply the value of each deal in your pipeline by its probability of closing. A $50,000 deal at the proposal stage with a historical 40% close rate contributes $20,000 to your forecast. Sum all deals across all stages and you have a weighted pipeline forecast.
This method requires accurate historical data on your conversion rates at each stage. If you do not have this data, start tracking it now. After three months, you will have enough to forecast meaningfully.
Account for Seasonality
Look at your sales data from the past two to three years and identify seasonal patterns. Most businesses have predictable peaks and troughs. Factor these patterns into your monthly forecasts rather than assuming even distribution across the year.
Forecast Multiple Scenarios
Create three forecasts: conservative (worst likely case), expected (most probable), and optimistic (best case). This range helps you plan for different outcomes and make contingency plans. Hiring decisions should be based on the conservative forecast. Inventory for perishable goods should use the expected forecast.
Review and Adjust Weekly
Compare actual results to your forecast weekly. If you are consistently missing in one direction, investigate why. Are you losing deals at a specific stage? Is a particular channel underperforming? Weekly reviews let you adjust course before small deviations become major problems.
Sales Team Input
Your reps have the closest view of what is actually happening with prospects. Incorporate their deal level assessments into your forecast, but apply a reality check. Sales teams tend to be optimistic. Applying a historical accuracy discount to rep forecasts improves overall accuracy.
Document Your Assumptions
Every forecast is built on assumptions about market conditions, competitive dynamics, and team capacity. Document these assumptions explicitly. When actual results differ from the forecast, you can identify which assumption was wrong and improve future predictions.