What is a good inventory turnover ratio for a manufacturer?

For most discrete manufacturers, 4 to 8 turns per year is healthy, equal to roughly 45 to 90 days of inventory. The worked example of 6.0 turns (61 days) sits comfortably mid-range. High-mix low-volume shops often run 3 to 5, while lean pull-based plants push 10 or more. Compare against your own industry segment, not a universal target, since acceptable turns vary widely by product type and lead time.

How do I calculate average inventory for the turns formula?

The simple method averages beginning and ending inventory: ($680,000 + $720,000) / 2 = $700,000. This works when stock is stable. For seasonal operations, average 12 monthly-ending balances instead, because a two-point average can badly misstate a plant that peaks mid-year. Always value inventory at cost using one consistent method, and match the period to the COGS window you divide into it.

Why use COGS instead of sales revenue for inventory turns?

COGS and inventory are both stated at cost, so dividing like by like gives a true velocity. Sales revenue includes markup, which inflates turns and makes the ratio meaningless for comparison. Using $4,200,000 COGS against $700,000 average inventory yields 6.0 turns. Substituting revenue of, say, $6,300,000 would falsely show 9.0 turns, overstating how fast physical stock actually moves through the plant.

How do I convert inventory turns into days of inventory?

Divide 365 by your turns figure. At 6.0 turns, that is 365 / 6.0 = 60.8, so about 61 days of inventory on hand. This days-of-supply view is often easier to act on than turns because it maps directly to lead times and safety stock. If your replenishment lead time is 30 days, 61 days on hand means you carry roughly two lead times of buffer.

My inventory turns dropped from 6 to 4. What causes that?

A drop from 6.0 to 4.0 turns means average inventory rose relative to COGS, pushing days on hand from 61 to 91. Common causes: overbuying ahead of forecast, slowing sales while purchasing continued, dead or obsolete SKUs piling up, or larger safety stock after a supplier scare. Segment by raw, WIP, and finished goods to find where the extra $350,000 of stock accumulated, then attack that tier.

What is the difference between inventory turns and days sales of inventory?

They are the same information expressed two ways. Turns is a frequency (6.0 times per year); days sales of inventory (DSI) is duration (365 / 6.0 = 61 days). Turns is handier for benchmark comparisons and financial reporting, while DSI is more intuitive for planners because it lines up against replenishment lead times. Use turns to compare plants, use days to set reorder and safety-stock policy.

Supply Chain and Inventory

Inventory Turns Formula

Inventory turns measures how many times inventory is sold and replaced in a period. Higher turns mean less working capital tied up in stock and lower carrying cost risk. Use it for benchmark comparisons, supplier negotiations, and lean inventory targets.

Formula

Inventory Turns = Cost of Goods Sold / Average Inventory

Variables

Cost of Goods Sold: Total manufacturing cost of all units sold in the period, in dollars
Average Inventory: Average on-hand inventory value during the period: (beginning inventory + ending inventory) / 2

Understanding the Inventory Turns Formula

Inventory turns tells you how hard your stock is working. Dividing COGS by average inventory converts a static balance-sheet number into a velocity figure: 6.0 turns means you cycle through the equivalent of your average stock six times a year. On the shop floor this is a direct proxy for tied-up working capital. Every extra turn frees cash, cuts warehouse space, and shrinks exposure to obsolescence, scrap, and price swings on raw material sitting in racks.

Pull COGS from the same 12-month window used for the inventory figures, and use manufacturing cost, not sales revenue, or you inflate the number. Average inventory should span the whole period; with $680,000 beginning and $720,000 ending, the simple average is $700,000, but seasonal plants should use a 12-month monthly average instead. Keep both terms at cost and in the same valuation method. Mixing revenue-based COGS with FIFO inventory produces a turns figure that means nothing.

Most discrete manufacturers land between 4 and 8 turns; 6.0 turns, or 61 days on hand, is solid mid-range. Below 3 turns (over 120 days) signals overbuying, dead SKUs, or slow lines. Above 10 can mean tight, disciplined pull systems or, if paired with stockouts, chronic underbuying. Do not chase turns blindly. Segment by raw, WIP, and finished goods, and act on the slowest tier first rather than a single blended number that hides the real offenders.

Worked Example

Annual COGS is $4,200,000. Beginning inventory was $680,000. Ending inventory was $720,000.

Average inventory = ($680,000 + $720,000) / 2 = $700,000
Inventory turns = $4,200,000 / $700,000 = 6.0 turns
Days of inventory = 365 / 6.0 = 60.8 days

Result: 6.0 turns per year (61 days of inventory on hand)

Common Mistake

Comparing turns across companies using different valuation methods. A company using FIFO costing may have a different inventory value than one using LIFO or average cost for the same physical stock. Always compare turns using the same cost accounting method.

Frequently Asked Questions

What is a good inventory turnover ratio for a manufacturer?: For most discrete manufacturers, 4 to 8 turns per year is healthy, equal to roughly 45 to 90 days of inventory. The worked example of 6.0 turns (61 days) sits comfortably mid-range. High-mix low-volume shops often run 3 to 5, while lean pull-based plants push 10 or more. Compare against your own industry segment, not a universal target, since acceptable turns vary widely by product type and lead time.
How do I calculate average inventory for the turns formula?: The simple method averages beginning and ending inventory: ($680,000 + $720,000) / 2 = $700,000. This works when stock is stable. For seasonal operations, average 12 monthly-ending balances instead, because a two-point average can badly misstate a plant that peaks mid-year. Always value inventory at cost using one consistent method, and match the period to the COGS window you divide into it.
Why use COGS instead of sales revenue for inventory turns?: COGS and inventory are both stated at cost, so dividing like by like gives a true velocity. Sales revenue includes markup, which inflates turns and makes the ratio meaningless for comparison. Using $4,200,000 COGS against $700,000 average inventory yields 6.0 turns. Substituting revenue of, say, $6,300,000 would falsely show 9.0 turns, overstating how fast physical stock actually moves through the plant.
How do I convert inventory turns into days of inventory?: Divide 365 by your turns figure. At 6.0 turns, that is 365 / 6.0 = 60.8, so about 61 days of inventory on hand. This days-of-supply view is often easier to act on than turns because it maps directly to lead times and safety stock. If your replenishment lead time is 30 days, 61 days on hand means you carry roughly two lead times of buffer.
My inventory turns dropped from 6 to 4. What causes that?: A drop from 6.0 to 4.0 turns means average inventory rose relative to COGS, pushing days on hand from 61 to 91. Common causes: overbuying ahead of forecast, slowing sales while purchasing continued, dead or obsolete SKUs piling up, or larger safety stock after a supplier scare. Segment by raw, WIP, and finished goods to find where the extra $350,000 of stock accumulated, then attack that tier.
What is the difference between inventory turns and days sales of inventory?: They are the same information expressed two ways. Turns is a frequency (6.0 times per year); days sales of inventory (DSI) is duration (365 / 6.0 = 61 days). Turns is handier for benchmark comparisons and financial reporting, while DSI is more intuitive for planners because it lines up against replenishment lead times. Use turns to compare plants, use days to set reorder and safety-stock policy.