Let Me Paint You a Picture
A customer walks up to your parts counter. They need one part. Your counter person looks it up, checks the shelf, and delivers the four words that make every dealer cringe:
“We’ll have to order that.”
The customer nods politely, maybe even says thanks. Then they walk out the door, get in their truck, and pull out their phone. They’re already searching before they hit the highway. That sale is gone, and honestly, depending on how loyal that customer was, they might be too.
Now multiply that by a dozen times a week. During your busiest season.
I know what you’re thinking. “Sara, we can’t stock everything.” And you’re right, you can’t. I’m not asking you to take on a billion(ish) dollars of new parts inventory. But I am asking you to think about whether the parts you should have on your shelf are actually there when someone asks for them.
That’s what the fill rate out of stocking inventory tells you. And if you don’t know yours right now, we need to have a little chat.
What Fill Rate Out of Stocking Inventory Actually Means
At its simplest, fill rate out of stocking inventory is the percentage of time someone asks for a part and you can hand it to them right then and there.
Three things count against that number.
Lost sales — which is the “crap, we didn’t have it” category.
Special orders — which is when a customer comes in asking for the most oddly specific part you’ve ever heard of and you have to track it down.
And emergency orders — which are the parts your service department needs yesterday, regardless of what it costs to get them there.
All of those count against your fill rate. Which is exactly why you’ll probably never hit 100%, and honestly, chasing 100% isn’t the smartest thing you can do with your cash anyway. I had a dealer once tell me he wanted his fill rate above 95%. I told him, “Listen, if you have all the money in the world and all the space, go for it, but for most dealers, it’s just not realistic. And the inventory investment to get there isn’t worth it.” The goal is 90. That’s the sweet spot. Here’s the formula:
Fill Rate = (Total Parts Sold – Lost Sales – Special Orders – Emergency Orders) / Total Parts Sold
Your target is 90 percent.
Think about that for a second. If 10 customers come in for a part today, you should be able to fill 9 of them from what’s already on your shelf. No ordering. No waiting. No “sorry about that.”
And here’s the thing, you already know what 90 percent feels like, because it’s exactly what you expect from your manufacturers. When you place a parts order, you expect them to have the parts in stock. You get frustrated when they don’t. You might (okay, you will) complain about it.
If you expect your manufacturer to have 90% of the parts you need in stock, your customers have every right to expect the same from you, too.
That’s not me being harsh. That’s just fair.
The Real Problem: You’re Not Tracking Lost Sales
Here’s where most dealers get stuck. They want to know their fill rate. They go to calculate it. And then they realize they have absolutely no idea what their lost sales number is.
And look, I get it. Most parts people let the customer walk out the door without taking the time to note which part they needed, usually because they are already helping the next person in line. It’s not laziness. It’s just busy.
But here’s the problem with that: without lost sales data, you can’t calculate a real fill rate. And without a real fill rate, you’re guessing at what to stock. And when you’re guessing, you’re going to keep stocking the wrong things, and keep sending customers down the road to someone who figured it out.
It’s a cycle. And you can break it with something as simple as a notepad at the parts counter.
Every time your counter person can’t fill a request from stock, they write down the part number. That’s it. You don’t need a fancy system to start. You just need the habit. A few weeks of that data and the picture gets very clear, very fast. You’ll probably be more than a little surprised by what you see.
The Fix Is Not What You Think
When I tell dealers their fill rate is low, the first thing they say is, “So we need to spend more on inventory?” I understand why they go there. But that’s not always the answer.
The goal isn’t to stock more. The goal is to stock smarter. We call it a wide-but-shallow inventory strategy.
Wide means you carry a large variety of parts, covering as many different requests as you can reasonably anticipate. Shallow means you don’t stock a mountain of any single part. A small quantity on hand. Enough to fill the need, not a year’s worth collecting dust.
Why shallow? Because most manufacturers can get you a restock within 48 hours. You’re not trying to be a warehouse. You’re trying to have what people need when they walk in.
Here’s the rule we give dealers: start stocking a part when you’ve had three unique customer requests for it over the course of a year. Stop stocking it when it’s had fewer than two requests in that same period. That keeps your inventory connected to actual demand instead of habit and gut feeling.
This isn’t a massive overhaul. It’s a discipline. And once you build it, your fill rate goes up, your emergency orders go down, and your customers stop leaving.
Start Here This Week
- Put a lost sales log at the parts counter. A notepad works. A shared spreadsheet works. Whatever your counter person will actually use. Every unfilled request gets written down. Part number, date, done.
- Pull your top 50 fastest-moving parts from the last 90 days and confirm they’re stocked at the right level right now. Running out of a fast-mover in season is a totally preventable problem.
- Count your special orders and emergency orders from last month. A high number of either means your stocking inventory isn’t matching demand. That’s a strategy problem, and now you know where to start.
Your fill rate is one of the clearest indicators of how well your parts department is run. A high fill rate means customers get what they need when they walk in. Your service techs aren’t waiting on parts. You’re not paying rush fees for things that never should have been emergencies.
A low fill rate means all of that is happening, quietly, repeatedly, every single week.
The number doesn’t lie. And now you know how to find it.
Stock what sells. Track what you miss. That’s how a parts department actually makes money.
Sara Hey is the President of Bob Clements International, a dealership consulting firm that works with tractor, OPE, RV, trailer, construction, and marine dealers across North America.