Seasonal Index Forecasting Explained — Excel Step-by-Step

Continue your forecasting and operations management learning with this hands-on seasonal index forecasting example in Microsoft Excel. In this video, Operations University instructor Brent Bolton demonstrates how to use historical data to calculate seasonal indexes and build a month-by-month forecast for the upcoming year. You’ll see how to compute monthly averages, calculate seasonal indexes, apply them to an annual forecast, and quickly update projections when demand assumptions change. This method is especially useful when demand follows predictable seasonal patterns. 👉 Get Certified (Lean Six Sigma) Watch the full Lean Six Sigma playlist, then complete your certification at OperationsUniversity.org to earn your Lean Six Sigma certificate. 💰 Advance Your Credentials Certification & Pricing = Yellow Belt $99 • Green Belt $499 • Black Belt $899 — or all 3 for $1,199 (save when purchasing together). Employer packages: Bulk enrollments & reporting available. 💡 What You’ll Learn in This Video: • What a seasonal index is and when to use it • How to calculate seasonal indexes from historical data • How to create a monthly forecast using Excel • How to adjust forecasts when annual demand changes • Why seasonal forecasting improves accuracy • Common mistakes to avoid in seasonal index calculations 📢 Call to Action ✅ Subscribe for more Lean Six Sigma & forecasting content ✅ Visit OperationsUniversity.org to get certified ✅ Share this video with planners, analysts, or students #LeanSixSigma #Forecasting #SeasonalIndex #ExcelForecasting #DemandPlanning #OperationsManagement