An auto shop's inventory is not the shop's work, it is the shop's money sitting on a shelf. Software sold as auto shop inventory software is usually sold to the service side, where the pitch is scheduling and invoicing and the stock is a lookup table bolted on. The parts department needs the opposite: a record that knows what is in each bin, what the system thinks is there, what has not moved in a year, and what all of that is worth at cost. This page sets out what the record has to hold before any of the reporting means anything, the four figures a parts operation actually runs on, and which free sheet on this site works each one from your own numbers with no account.
What the record has to hold
Six things, each with a status and a date: the part with its number and its interchange, the bin it lives in, every count against it, every reorder raised on it, the supplier it came from, and every price change. Software that keeps parts and bins but not counts cannot tell you your accuracy. Software that keeps counts but not price history cannot tell you what a margin was last quarter. The test in a demo is simple and almost nobody runs it: ask to see one part number's whole history on one screen, its counts, its reorders and its price changes together. If that takes three screens, the record is three lists in a trench coat and every figure below has to be rebuilt by hand each time you want it.
Repair shop inventory management is a different job from shop management
Repair shop inventory management is about the parts the shop consumes and sells; shop management software is about the work the shop books. They overlap at the repair order and nowhere else. It matters when you buy, because a shop management system that includes inventory usually includes enough of it to look complete in a demo and not enough to count with: no cycle-count support, no variance at cost, no dead-stock ageing, and a reorder point that is a static minimum somebody typed in two years ago. If the parts are the thing tying up your cash, buy for the parts record and make the service side fit it, not the other way round.
The four figures the software should be working for you
Inventory accuracy, the reorder point, margin and turns. Accuracy is what proportion of counted lines matched the system, and it is the figure everything else depends on: on the stock count sheet here, 300 lines counted with 261 matching is 87% accuracy, 39 lines wrong, and the variance priced at cost. The reorder point is usage, lead time and safety cover, and the sheet works it at 12 units a week with a seven day lead. Margin is what the counter actually took after the discount it really gives, not the list price. Turns is cost of goods sold against average inventory value, and on the turns sheet $420,000 sold against $105,000 held is four turns and 91 days on hand. If the software you are looking at will not show you those four, the sheets on this site will, today, from your own figures.
What the free sheets do instead of a trial
Every figure above is worked here without an account: a stock count sheet for accuracy and variance, a reorder point sheet for when to order, a parts margin sheet for what the counter really made, an inventory turns sheet for days on hand and the cash a target would release, and a dead stock sheet for the shelf that has stopped moving. They are the arithmetic a parts inventory system does, separated from the record it keeps, so you can put your own numbers through them before you commit to anybody's software. The subscription on this site keeps the record those figures come out of; the sheets stay free either way.
Questions people ask about auto shop inventory software
Is auto shop inventory software the same as shop management software?
No. Shop management software is built around the work the shop books: the repair order, the technician, the invoice. Inventory software is built around the stock the shop holds: the part, the bin, the count and the reorder. Many shop management systems include an inventory module, and the question to ask about it is whether it supports cycle counts, prices the variance at cost and ages dead stock. If it does not, it is a lookup table.
What should repair shop inventory management measure first?
Inventory accuracy, because every other figure is derived from a record you have not proved. Count a sample of lines, compare what you found to what the system claimed, and work the proportion that matched. The stock count sheet on this site does it from your counted lines and average unit cost, and returns the accuracy, the lines that missed, the unit variance and what that variance is worth.
How often should a parts department count?
Continuously rather than annually, in small cycles. A full annual count tells you your accuracy once a year and closes the counter to do it; cycle counting a slice of the shelf each week tells you the same thing continuously and catches the process fault that caused the variance while anyone can still remember it. What matters is that the count is compared to the system and priced, not that it is exhaustive.
Do I need software before I can work these figures?
No, and that is the point of the sheets here. Accuracy, reorder point, margin, turns and dead stock are arithmetic on numbers you already have. Working them by hand first also tells you what to demand of any system you buy, because you will know which of the five it can actually produce.