Inventory Forecasting for Supply Chain Disruptions
Compare inventory forecasting methods for disruption planning and see how OLT uses recent movement history, allocatable stock, and multiple projection horizons.
Modern Safety Stock Calculations
Buyer Evaluation Guidance
Forget static weeks-of-supply rules. Modern safety stock incorporates the Standard Deviation of Lead Time, demand volatility, and service level targets into a unified formula.
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Lead Time Variability
Standard Deviation of Lead Time measures how unpredictable your supplier delivery windows are. Higher variability demands higher safety stock.
σLT = √(Σ(LTi - μLT)² / n)- Lead-time variability input
- σLT
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Demand Volatility
Demand Sensing captures real-time consumption patterns rather than relying on historical averages that may no longer apply.
σD = Standard Deviation of Daily Demand- Demand variability input
- σD
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Service Level Target
Z-score determines how much buffer you need. 95% service level requires Z=1.65; 99% requires Z=2.33.
Z × σ = Safety Stock Buffer- Chosen service-level factor
- Z
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Combined Formula
Modern safety stock calculation combines lead time variability with demand uncertainty using the root-sum-square method.
SS = Z × √(LT×σD² + D²×σLT²)- Calculated safety-stock quantity
- SS
Current OLT inventory forecast workflow
The shipped OLT inventory forecast summarizes recorded customer-demand movements in three 30-day history buckets, shows current allocatable and on-hand stock, and returns minimum, central, and maximum projections for 30, 60, 90, and 180 days.
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Three 30-day demand buckets
Customer-demand stock movements from the latest 0–30, 30–60, and 60–90 day windows form the demand-history baseline; internal transfers do not count as demand.
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Allocatable and on-hand stock
Current stock and days supply use allocatable units after reservations and active holds are excluded, while physical on-hand stock remains visible separately.
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Trend and season classifications
Simple demand-history thresholds classify trend as up, down, or stable and season as peak, low, or stable for each SKU.
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Four forecast horizons
The workflow shows 30-, 60-, 90-, and 180-day projections with a minimum, central value, and maximum for each horizon.
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Warehouse and SKU filters
Planners can scope movement history and allocatable stock to a warehouse, search active products by SKU, and page through the matching products.
- Inventory Optimization: A Practical Guide to Carrying Cost and Working Capital Learn how carrying cost formulas, ABC analysis, reorder planning, dead-stock reviews, and your own assumptions support inventory decisions.