ABC-XYZ Inventory Analysis Calculator
Classify inventory items by annual value (ABC) and demand variability (XYZ) to prioritize stock management. Use this when optimizing reorder policies, safety stock levels, or supplier negotiations across a large product portfolio.
About this calculator
ABC-XYZ analysis combines two classification frameworks. ABC ranks items by their percentage of total annual usage value: A items typically represent ~80% of value (top 20% of SKUs), B items ~15%, and C items ~5%. XYZ classifies items by demand predictability using the coefficient of variation (CV = standard deviation / mean demand × 100): X items have CV below 20% (stable demand), Y items 20–50%, and Z items above 50% (highly erratic). The combined score used here is: Score = (annualUsageValue / totalInventoryValue × 100) × (demandCV / 100) × (forecastAccuracy / 100). A high score indicates a high-value item with volatile, hard-to-forecast demand — an AZ item — which requires the tightest inventory controls and largest safety buffers. BX or CX items can be managed with leaner, more automated replenishment.
How to use
Suppose a SKU has an annual usage value of $50,000, total inventory value is $500,000, a demand coefficient of variation of 40%, and forecast accuracy of 85%. Step 1: Value share = $50,000 / $500,000 × 100 = 10%. Step 2: Apply the formula: Score = 10 × (40 / 100) × (85 / 100) = 10 × 0.40 × 0.85 = 3.40. Step 3: With a value share of 10% this item falls in the B tier, and a CV of 40% places it in the Y demand class — making it a BY item requiring moderate safety stock and periodic demand review.
Frequently asked questions
What is the difference between ABC and XYZ inventory analysis?
ABC analysis ranks inventory items by their financial impact, measured as each item's share of total annual usage value. XYZ analysis ranks items by demand predictability, using the coefficient of variation to identify stable (X), moderately variable (Y), and highly erratic (Z) demand patterns. When combined into ABC-XYZ, you get a 3×3 matrix that guides both replenishment strategy and safety stock sizing. For example, AX items are high-value and predictable — ideal for lean, just-in-time replenishment — while AZ items are high-value but volatile, demanding larger buffers and closer supplier coordination.
How do you calculate the coefficient of variation for XYZ classification?
The coefficient of variation (CV) is calculated as: CV = (standard deviation of demand / mean demand) × 100. You collect periodic demand data — typically monthly figures over 12 months — compute the mean and standard deviation, then divide. A CV below 20% classifies the item as X (highly predictable), 20–50% as Y (moderate variability), and above 50% as Z (unpredictable). Using at least 12 data points is recommended to get a statistically meaningful CV; fewer periods can produce misleadingly low or high values.
When should I use ABC-XYZ analysis instead of simple ABC analysis alone?
Simple ABC analysis alone tells you which items are financially important but says nothing about how reliably you can forecast their demand. You should layer in XYZ analysis whenever demand patterns across your SKU base vary widely — for example, in retail, spare-parts distribution, or seasonal industries. An item can be low-value (C class) yet highly erratic (Z class), meaning it unexpectedly ties up cash in safety stock. ABC-XYZ ensures that inventory policies account for both value impact and demand uncertainty, leading to more targeted service-level agreements and reorder rules.