Inventory turnover calculator for spare parts
How many times a year your parts stock turns over, and how many days a part sits on the shelf on average, from what you used and what you stocked.
Your numbers
See your resultResult
Inventory turnover 4.00 turns a year Days in inventory 91.3 dayshow long a part sits, on average Average inventory $45,000(start + end) ÷ 2 Parts used per day $493 Stop working this out by handFleetZap counts parts in and out on every work order, with reorder points, low-stock alerts and purchase orders, so you can see which parts move and which sit.
See FleetZap Maintenance · Try the demoThe formula
Inventory turnover = Parts used at cost ÷ Average inventory · Days in inventory = 365 ÷ Turnover
With the example: $180,000 ÷ (($50,000 + $40,000) ÷ 2) = 4.0 turns a year, so a part sits about 91 days. For a sales business the same formula uses cost of goods sold. A whole-store number hides a lot: the ABC analysis guide splits fast movers from parts that never leave the shelf.
Using the numberWhat to do with it
- Low turnover on a part you rarely need can still be right: a critical spare that stops a machine is worth keeping. Judge turnover by class of part.
- Parts that haven’t moved in a year or more are cash on a shelf. Return, sell or stop restocking them.
- Raising turnover by cutting stock only works if reorder points keep the parts that matter in stock.
Guides behind this calculator
Spare parts inventory ABC inventory analysis Parts inventory softwareMore free calculators
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The heart of FleetZap, and everything a maintenance team needs in one place: work orders and preventive maintenance, inspections and the field app, plus a parts store with purchasing, compliance and certificate tracking, multi-location assets with a full lifecycle, and the KPIs that prove it’s working.
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Good to know
What is the inventory turnover formula?Inventory turnover = cost of parts used (or cost of goods sold) ÷ average inventory, where average inventory is (start + end) ÷ 2. $180,000 used on a $45,000 average is 4 turns a year.
How do you calculate days in inventory?Divide 365 by the turnover ratio. At 4 turns a year, a part sits about 91 days on average.
What is a good inventory turnover for spare parts?It depends on the part. Fast-moving filters and wear parts should turn often; critical spares may turn once a year or less and still be worth keeping. Compare by class of part, not one number for the store.
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