What is Inventory Turnover? Definition & Manufacturing Examples

What is Inventory Turnover?

Inventory turnover (also called inventory turns) is a financial and operational metric that measures how many times a company sells and replaces its inventory during a given period. It indicates how efficiently a manufacturer converts inventory investment into revenue. The higher the turnover ratio, the less time inventory sits in storage, the lower the carrying costs, and the more efficiently working capital is utilized.

The formula is: Inventory Turnover = Cost of Goods Sold (COGS) / Average Inventory Value

A turnover ratio of 6 means the company sells and replaces its entire inventory six times per year, or roughly every two months. A ratio of 12 means inventory turns over monthly.

Inventory turnover is one of the most important operational metrics for manufacturers because it captures the combined effectiveness of demand planning, production scheduling, purchasing, and inventory management in a single number. Low turnover signals excess inventory, poor demand alignment, or both. High turnover indicates lean operations but may signal insufficient stock if it comes at the cost of customer service.

How Inventory Turnover Works in Manufacturing

Inventory turnover can be calculated for total inventory or broken down by category:

Total inventory turnover = COGS / Average total inventory (raw materials + WIP + finished goods)

Raw material turnover = Material consumed / Average raw material inventory

WIP turnover = COGS / Average WIP inventory

Finished goods turnover = COGS / Average finished goods inventory

Each component tells a different story. Low raw material turnover suggests over-purchasing or poor supplier management. Low WIP turnover indicates production bottlenecks or long manufacturing lead times. Low finished goods turnover signals overproduction or weak demand.

A related metric is Days Inventory Outstanding (DIO): DIO = 365 / Inventory Turnover. This converts the turnover ratio into the average number of days inventory is held before being sold. A turnover of 6 equals a DIO of approximately 61 days.

Manufacturers track turnover trends over time. Improving turnover from 4 to 6 turns while maintaining or improving customer service levels indicates meaningful operational improvement. Declining turnover is a warning signal that requires investigation.

Inventory Turnover Example

A mid-size manufacturer of hydraulic components has the following annual data:

• Cost of Goods Sold: $18,000,000
• Average Raw Materials: $1,200,000
• Average WIP: $800,000
• Average Finished Goods: $1,000,000
• Average Total Inventory: $3,000,000

Total inventory turnover = $18,000,000 / $3,000,000 = 6.0 turns Days inventory outstanding = 365 / 6.0 = 61 days

Industry benchmark for hydraulic component manufacturers: 7-8 turns. The company is below benchmark, indicating improvement opportunity.

Analysis by category reveals:

• Raw material turnover: $10,800,000 consumed / $1,200,000 = 9.0 turns (healthy)
• WIP turnover: $18,000,000 / $800,000 = 22.5 turns (good — lean manufacturing)
• Finished goods turnover: $18,000,000 / $1,000,000 = 18.0 turns (good)

Wait — the total turnover of 6.0 seems inconsistent with the component turnovers. This is because the components use different numerators. When normalized, the analysis reveals that raw material inventory is the primary opportunity area, holding more stock than necessary.

By implementing vendor-managed inventory for A-class raw materials and reducing order quantities to align with EOQ, the company reduces average raw material inventory to $900,000. New total inventory: $2,700,000. New turnover: 6.7 turns — a 12% improvement that frees $300,000 in working capital.

Why Inventory Turnover Matters for Production Scheduling

Inventory turnover and production scheduling are deeply interconnected. Every scheduling decision affects inventory levels: large batch sizes increase average inventory (lower turnover), while smaller, more frequent batches reduce it (higher turnover).

Scheduling software like Resource Manager DB helps manufacturers optimize production batch sizes and timing to improve turnover without sacrificing customer service. By aligning production schedules more closely with actual demand, manufacturers reduce the time materials spend as WIP and finished goods.

Effective scheduling also reduces raw material inventory by coordinating purchase deliveries with production start dates. When material arrives just before it is needed rather than weeks in advance, raw material turnover improves.

Improving inventory turnover is one of the most tangible financial benefits of better production scheduling — freeing working capital, reducing carrying costs, and improving return on assets.

Related Terms

• Days Inventory Outstanding — the number of days of inventory on hand, derived from turnover
• Carrying Cost — the holding costs that decrease as turnover improves
• WIP Inventory — in-process inventory whose turnover reflects manufacturing efficiency

FAQ

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This term is part of our Manufacturing & Production Scheduling Glossary. Learn more about inventory management, scheduling, and manufacturing terminology.