Vendor-managed inventory (VMI) has become a powerful strategy in the building materials sector—offering reduced stockouts, better supply chain visibility, and stronger distributor-vendor relationships. But success with VMI doesn’t happen by chance.
To run an effective VMI program, suppliers and distributors must go beyond basic stock levels and monitor key performance indicators (KPIs) that reflect how well the program is performing—operationally, financially, and in terms of customer service.
Here are the essential KPIs to track for an efficient and reliable VMI program in your building supply chain.
- Stock Availability Rate (or Fill Rate)
What it measures:
The percentage of demand fulfilled directly from VMI stock without delay.
Why it matters:
This KPI reflects the primary goal of VMI: keeping the right products in stock at all times.
Target: 95%+ fill rate to maintain contractor service levels without excess inventory.
- Stockout Frequency and Duration
What it measures:
How often and how long VMI-managed products are unavailable when needed.
Why it matters:
Frequent or long stockouts can halt construction projects and damage customer trust.
Use this KPI to:
Flag poor forecasting
Identify slow replenishment cycles
Improve supplier lead time reliability
- Inventory Turnover Ratio
What it measures:
How often VMI stock is used and replenished over a specific period.
Why it matters:
A healthy turnover rate indicates efficient inventory flow, minimal holding costs, and accurate demand forecasting.
Formula:
Cost of Goods Sold / Average Inventory
Best practice: Benchmark turnover by category (e.g., fasteners vs. bulk concrete forms).
- Days of Supply (Inventory Coverage)
What it measures:
How many days current VMI inventory will last based on historical usage.
Why it matters:
Too high = tied-up capital. Too low = risk of stockouts.
Target:
Maintain a balanced inventory level that ensures supply while minimizing overstock—especially during peak construction seasons.
- Forecast Accuracy (Demand Planning Error Rate)
What it measures:
The difference between projected and actual product demand.
Why it matters:
Accurate forecasting is the backbone of effective VMI. Poor accuracy leads to overstocking or missed deliveries.
Track by:
Product category
Region
Vendor
Goal: Continuous improvement through seasonal and job-specific demand adjustments.
- Replenishment Lead Time
What it measures:
The average time it takes for vendors to replenish stock after a reorder point is triggered.
Why it matters:
Long or inconsistent lead times affect your ability to maintain optimal inventory levels.
Use this KPI to:
Assess vendor responsiveness
Improve scheduling and buffer stock planning
Negotiate better SLAs with key suppliers
- Order Accuracy and Delivery Performance
What it measures:
The percentage of VMI deliveries that are on time and correct.
Why it matters:
Even the best forecast fails if deliveries are late or inaccurate.
KPI breakdown:
On-time delivery rate
Complete delivery rate
Correct item and quantity fulfillment
- Return and Obsolescence Rate
What it measures:
The percentage of VMI-managed products that are returned or become obsolete before use.
Why it matters:
High rates may indicate over-ordering, misaligned forecasting, or a mismatch between inventory and real-world demand.
Goal:
Minimize holding of slow-moving SKUs through better product lifecycle planning.
- Cost to Serve per SKU or Location
What it measures:
The total cost of managing each product or location under VMI—including replenishment, transportation, and storage.
Why it matters:
Helps determine the true ROI of the VMI program and identify where it works best.
Use this KPI to:
Compare managed vs. non-managed inventory and make data-driven expansion or scaling decisions.
- Vendor Performance Scorecard
What it combines:
A holistic view of each vendor’s performance across multiple VMI KPIs, including:
Fill rate
Lead time
Forecast accuracy
On-time delivery
Return rate
Why it matters:
Supports regular business reviews, vendor negotiations, and continuous improvement initiatives.
Final Thoughts
Vendor-managed inventory can unlock massive efficiency gains in the building materials supply chain—but only when it’s tracked and managed with the right metrics.
By monitoring these KPIs, suppliers and distributors can:
Reduce capital tied up in inventory
Improve contractor satisfaction
Build stronger, more accountable vendor relationships
Make smarter replenishment and stocking decisions
VMI success isn’t just about stocking shelves—it’s about strategic, measurable supply chain alignment.
