Forecasts built on gut feel and end-of-quarter conversations are easy to challenge. Here's how to build one that's evidence-based and defensible.
The classic sales forecast problem: your board asks for a number. Your VP Sales talks to their managers. Their managers talk to their reps. Everyone applies a layer of optimism. The number that comes back is 20% higher than what actually closes. Every quarter.
Boards learn to discount the forecast. Reps learn to sandbag to look good. The whole system drifts toward unreliability. Here's how to break that cycle.
Start with real pipeline data
A credible forecast starts with a pipeline that's actually up to date. Stale close dates, deals that haven't been touched in 30 days, and opportunities with no next step logged are all forecast noise. Clean the pipeline first — then build the model.
Use historical conversion rates
The most reliable input to a forecast is your own historical conversion data. What percentage of deals at each stage actually close? What's the average time between stages? Apply these rates to your current pipeline and you get a probability-weighted forecast that's much harder to argue with than a manager's instinct.
- Stage 1 → Close: track historical conversion per stage
- Average days between stages: identifies where deals stall
- Win rate by segment, rep and deal size: spots patterns
- Deal slippage rate: how often does the close date move?
Three categories, not one number
The best forecasts don't present a single number — they present three: Committed (deals with verbal or written commitment that are tracking to close this period), Best Case (committed plus upside that's realistic), and Pipeline (the theoretical maximum if everything closes). This gives the board a range to plan against and makes the assumptions transparent.
Review it weekly
A forecast reviewed once a month is already outdated. The best teams review their forecast every week — not to change the number, but to update it based on what's actually happened. Deals that slipped get moved. Deals that accelerated get promoted. The forecast stays current.
“A forecast isn't a promise. It's your best current estimate of what will happen, updated as you learn more. Treat it like a living document, not a commitment you're afraid to revise.”
Aonsight's Sales Forecasting and Pipeline Board give you a live, probability-weighted forecast grounded in real pipeline data — updated continuously as deals progress.