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6 essential calculators used daily by demand planners and supply chain managers across GCC & MENA. Instant results, formula explanations, free forever.
Formula (Greasley's combined variability model):
SS = Z × √(LT × σ_d² + D̄² × σ_lt²)
Where: Z = service level z-score, LT = avg lead time (days), σ_d = daily demand std dev, D̄ = avg daily demand, σ_lt = lead time std dev.
Reorder Point: ROP = (D̄ × LT) + SS
GCC note: In the UAE/GCC market, always add a Ramadan surge buffer (typically +15–25%) on demand-sensitive FMCG SKUs during Ramadan planning cycles.
Wilson EOQ Formula:
EOQ = √(2 × D × S / H)
Where: D = annual demand (units), S = ordering cost per order, H = annual holding cost per unit.
Total Annual Cost: TC = (D/Q)×S + (Q/2)×H
GCC context: In Dubai/GCC distribution, high warehouse rental costs (AED 35–80/sqm/month in JAFZA/DIP) mean holding costs are typically 25–35% of unit cost — higher than the global benchmark of 20–25%. Use this when estimating H from unit cost.
Standard Reorder Point:
ROP = (Avg Daily Demand × Lead Time) + Safety Stock
Maximum Reorder Point (conservative):
Max ROP = (Max Daily Demand × Max Lead Time) − (Avg Daily Demand × Avg Lead Time)
When to use Max ROP: Use the conservative ROP for A-class high-value SKUs or for suppliers with historically unreliable lead times (e.g., cross-border suppliers via Jebel Ali during Red Sea disruption periods).
Enter actual vs forecast values (up to 12 periods). Leave unused rows blank.
MAPE: MAPE = (1/n) × Σ |Actual − Forecast| / Actual × 100%
Forecast Accuracy: FA = 100% − MAPE
Bias: Bias = (1/n) × Σ (Forecast − Actual) / Actual × 100%
Positive bias = over-forecasting. Negative = under-forecasting.
Benchmarks (GCC FMCG): World class ≥95% | Good ≥90% | Acceptable ≥80% | Needs improvement <80%.
Limitation: MAPE is undefined when Actual = 0. Use sMAPE or WAPE for intermittent demand SKUs.
Inventory Turnover: IT = COGS / Avg Inventory Value
Days of Inventory: DOI = Period Days / IT
GCC benchmarks by sector (Gartner 2024):
FMCG: 7–10× | Automotive: 5–8× | Electronics: 6–10× | Fashion: 4–6× | Pharma: 5–8× | Industrial: 4–6×
Tip: Low turnover can signal overstocking or slow-moving SKUs. High turnover may mean lean operations but can increase stockout risk — use alongside fill rate and safety stock metrics.
Total Carrying Cost Rate:
CCR = Capital % + Storage % + Obsolescence % + Insurance %
Annual Carrying Cost: ACC = Avg Inventory Value × CCR
GCC / UAE context:
Capital cost: UAE 5-year rate ~4–6% (2024). JAFZA/DIP warehouse storage: 5–9% of inventory value. Obsolescence for FMCG: 3–7%. Total GCC range: typically 18–32%.
A 1% reduction in carrying cost rate on AED 10M inventory = AED 100,000 per year — use this to justify safety stock optimisation projects.