Inventory Turnover Calculator for Manufacturers
Calculate turnover and days inventory separately for raw materials, WIP, and finished goods — not one blended number.
Raw Materials
Turnover
5x
Days Inventory
73
Work in Progress (WIP)
Turnover
19.2x
Days Inventory
19
Finished Goods
Turnover
7.1x
Days Inventory
52
Turnover = Cost Flow ÷ Average Inventory · Average Inventory = (Beginning + Ending) ÷ 2 · Days Inventory = 365 ÷ Turnover
For comparison, a blended single-number turnover (COGS ÷ combined average inventory across all three stages) would show 3.5x — obscuring how much faster WIP moves than raw materials or finished goods.
The formula
Inventory turnover divides how much cost flowed out of a stage of inventory by the average amount held there during the period:
Turnover = Cost Flow ÷ Average Inventory
Average Inventory = (Beginning Inventory + Ending Inventory) ÷ 2
Days Inventory = 365 ÷ Turnover
Most turnover calculators and templates apply this once, to a single blended inventory number. Manufacturers get a more useful answer by applying it three times — once each for raw materials, WIP, and finished goods — since each stage has a different cost flow and moves at a different speed.
Worked example: three stages, three different stories
A manufacturer pulls a year of data for each inventory stage:
Raw Materials: $200,000 used ÷ avg $40,000 ($30,000 beginning, $50,000 ending) = 5.0x turnover, 73 days
WIP: $480,000 COGM ÷ avg $25,000 ($20,000 beginning, $30,000 ending) = 19.2x turnover, 19 days
Finished Goods: $460,000 COGS ÷ avg $65,000 ($60,000 beginning, $70,000 ending) = 7.1x turnover, 52 days
A blended calculation — $460,000 COGS divided by the combined average inventory of $130,000 across all three stages — would report a single 3.5x turnover, about 103 days. That number hides the real story: raw materials are the slow point, sitting for 73 days before they even enter production, while WIP moves through in under three weeks. A purchasing or supplier-terms fix targets raw materials specifically; a blended number wouldn't have pointed there.
Related calculations
WIP turnover depends on Cost of Goods Manufactured, and finished goods turnover depends on COGS — calculate those first if you don't already have the numbers. See the full definitions of Inventory Turnover and WIP (Work in Progress) in the glossary, or read Inventory Turnover Ratio for Manufacturers: How to Calculate and Read It and Inventory Aging Report: Spot Slow-Moving Stock Before It Costs You. If turnover looks off because the underlying counts are unreliable, the spreadsheet cost calculator puts a number on what manual tracking is costing you.
More free calculators
Frequently asked questions
What is inventory turnover?
Inventory turnover measures how many times a business sells through and replaces its inventory in a period, calculated as cost flow (COGS, or the equivalent cost transferred out) divided by average inventory. A higher turnover generally means inventory is moving efficiently; a lower turnover can signal overstocking, slow-moving items, or production bottlenecks.
Why calculate turnover separately for raw materials, WIP, and finished goods?
A single blended turnover number hides where the actual problem is. A manufacturer might show a healthy overall turnover while sitting on raw materials that barely move — the fast-turning WIP and finished goods stages mask it. Splitting turnover by stage shows exactly which part of the production pipeline is tying up cash: purchasing (raw materials), the shop floor (WIP), or sales (finished goods).
What counts as the "cost flow" for each inventory stage?
For raw materials, use the cost of raw materials consumed in production during the period. For WIP, use Cost of Goods Manufactured (COGM) — the cost of everything transferred out of WIP into finished goods. For finished goods, use Cost of Goods Sold (COGS) — the cost of everything that shipped. Each stage uses the cost flowing out of it, not revenue.
What is a good inventory turnover ratio for a manufacturer?
It depends heavily on industry and product type — perishable food manufacturers often turn raw materials and finished goods 15-20+ times a year, while durable goods or made-to-stock manufacturers with longer production cycles may run 4-8 times a year. The more useful benchmark is your own trend over time and the mix across stages, not a single external number.
See turnover by stage automatically in Nstock
Nstock tracks raw materials, WIP, and finished goods inventory separately in real time, so turnover and days-inventory reports by stage are always current instead of a manual quarterly pull.