Back bar inventory management: finish the system you already have

A colorist squeezes the last of a tube of 6N into the bowl, tears the top off the box and drops it into a tub by the sink. On Friday somebody tips the tub out on the desk and reorders from whatever is in it.

If that is how your salon runs the back bar, you are further along than most articles give you credit for. That tub is a real inventory system. It just has a few blind spots, and they tend to show up in the middle of a color correction.

This is how to finish that system: two numbers per product, a way to work out how much to keep, one rule for half-used bottles, and a simple check on whether what left the shelf matches the work you did. Nothing here asks anyone to log product in the middle of a service. For the wider picture, start with our guide to salon inventory management.

👀 Why back bar is the half you can't see

Retail leaves a receipt. Every bottle that goes out the door with a client shows up in a sales report, so you always have a second number to check the shelf against.

Back bar leaves nothing. It goes into services, never becomes a sale, and never appears in any figure your booking system or till produces. Every method built for retail assumes a sales number to reconcile against, and back bar has none. So owners tend to see the smaller half of their stock clearly and guess at the larger half.

That is also why back bar is worth the effort. Strategies, Neil Ducoff's salon and spa consultancy, puts professional product at four to six percent of service revenue, and Lisa M. Starr of Wynne Business puts hair departments at 6–7% and skincare at 5–8%. On a salon doing $200,000 in services, that is somewhere between $8,000 and $16,000 a year of product nobody ever rings up.

The good news is that most salons already have the start of a method. It is sitting next to the sink.

🗑️ You already have a system: the box-top bin

The tub of torn box tops, caps and tabs is what supply-chain people call a pull signal. Nobody counts anything. An empty package simply says "replace me", and someone reorders from the pile on a set day.

Hospitals run the same idea on purpose. In the two-bin system described by Rosales, Magazine and Rao in the European Journal of Operational Research, each supply sits in two bins; when the first empties, it goes back for refilling while staff work from the second, and the hospital tracks empty bins and never individual units. It was designed for hundreds of cheap, fast-moving items. That is a fair description of a color bar.

What the bin gets right:

• No memory required. The empty package is the note.
• Nothing to log during a service.
• It works on the busiest Saturday of the year.

Where it goes quiet:

• It tells you what already ran out, never what is about to.
• It says nothing about how much is left in the back.
• It fails silently the first week somebody forgets to tear the tab.
• It has no memory. Last month's bin is in the trash.

Keep the bin. Those four gaps are what to close around it, starting with the one that causes the most mid-service panic.

📍 Two numbers per product: station and stockroom

The most common back bar story goes like this: the stockroom has three tubes of a shade, and the colorist at station two runs out mid-application because none of them made it to the floor.

One number per product cannot show that problem. Two numbers show it straight away:

• At the station: what a pro can reach without leaving the client. Enough for a day or two of services.
• In the stockroom: everything else, the buffer that refills the stations.

When the station number drops, you move product from the back. When the stockroom number drops, you order. Keeping them apart turns one vague worry into two clear jobs, and it matches how the room is physically built.

Our salon inventory spreadsheet template is set up this way, with a column for each place and a total, so you can see both numbers on one line.

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🔢 How much to keep, and how to work it out

Successful owners disagree about this. Some order weekly to keep cash free, some keep a deliberate two-month buffer, some run as lean as they dare. Which of those suits your salon depends on your cash and your suppliers, so here is the arithmetic that produces your own number:

How much you use in a day × days between deliveries + a buffer for the delivery that runs late.

Run it once on one real product. Say your colorists go through three tubes of 6N a week, over a six-day week. That is half a tube a day. Your supplier delivers once a week, so seven days between deliveries: 0.5 × 7 = 3.5 tubes. Deliveries sometimes slip by up to three days, so add 0.5 × 3 = 1.5 tubes as buffer. Order when five tubes in total are left: two at the stations and three in the stockroom.

That number is not set for life. Seasons shift it, a new colorist shifts it, a supplier that changes its delivery day shifts it. Look at it again every few months, and treat every stockout as a signal that the number was too low. The difference between the level you keep and the point at which you reorder is a subject of its own, covered in our piece on reorder point versus par level.

In Suplery you enter each count from your phone as you do it. After a couple of counts it sees how fast each product actually goes and starts drafting reorders for you, one per supplier, waiting for your approval.

Price, though, is the wrong way to decide which products deserve the most attention.

🧤 The cheap thing that stops the chair

Most advice says to watch the expensive items. In a real salon, the service usually stops over something cheap: developer, gloves, foils, applicator brushes, the one toner everybody reaches for.

So sort by a second question: if this ran out right now, would a service stop? If the answer is yes, keep a little more of it than the arithmetic says, whatever it costs. A few extra boxes of gloves tie up almost no cash. Rebooking a client ties up a lot of goodwill.

Deciding which products get the most attention across the whole back bar is its own method, covered in our guide to ABC analysis for salon inventory.

🫙 The half-used ones

Every count runs into the same bottles: open, partly used, impossible to call. My rule is simple: count full, unopened units only. Open containers are in use, and they stay out of the count.

The reason is consistency. A half-empty bottle has no honest number. One person calls it a half, the next calls it a third, and your count becomes an opinion that changes with whoever is holding it. Counting sealed units only gives you a slight undercount that is the same every week, and a consistent number is the only kind you can compare with last week's.

Whatever rule you choose, write it at the top of the sheet and never mix rules between counts. How to run the count itself, from where to start to what to do with the gaps, is in our guide to how to do inventory in a salon.

⚖️ Does what left the shelf match the work you did?

This is the question behind most back bar worry, and it is easier to answer than it sounds, as long as you keep it small.

Take one product for one week. Count it on Monday and again the next Monday, adding what arrived in between. That gives you what actually left the shelf. Then look at the services on the books for the same week and estimate what they should have used.

If the two are close, relax. If they disagree badly, week after week, the gap is one of three things: over-application, waste at the bowl, or product walking out. The check points you at the product worth watching, and from there you can find out which of the three it is. Reducing waste at the bowl is its own subject, in our piece on beauty salon back bar waste.

Be honest with yourself about the limit here. This check works by hand for one product at a time. Across a whole back bar, every week, it is a part-time job, and that is the point where keeping it on paper stops paying.

📅 Who orders, and on what trigger

The most common reordering rule in salons is "when we notice". It is also the one that produces the most emergency orders at full price.

The smallest change with the biggest effect is three decisions, written down:

• Who orders back bar. One named person, with a deputy for their days off.
• Which day they do it. A fixed day survives a busy month; a vague "weekly" rarely does.
• What triggers an order. The bin, plus anything below the level you worked out above.

The order list tab in the spreadsheet template does this for you by pulling every product that has dropped below its level. In Suplery, once your counts are in, the draft order is already built per supplier when that day comes around, so the named person only has to review and send it. Past a handful of suppliers, that is the difference between a ten-minute job and an evening, which is what salon inventory management software is for.

💬 A note on the back bar fee

If you got here looking for whether a back bar fee taken out of a stylist's commission is fair, that is a different question. This article is written for whoever buys the product.

🧡 The bin, finished

Keep the tub by the sink, and build the rest around it: two numbers per product, a level worked out from how fast it actually goes, one rule for open bottles, and one person who orders on one day.

Suplery keeps those numbers for you: product added by photo or barcode scan, counts entered by anyone on the team from their own phone, and after a couple of counts, a draft order per supplier built from how fast each product really goes.

👉 Start on Suplery

What counts as back bar and what counts as retail?

Back bar (also written backbar) is professional product used in services and never sold: color, developer, shampoo at the bowl, wax, masks, disposables. Retail is product sold to clients to take home. Same shelf sometimes, completely different logic.

How do you track back bar when it is never scanned or sold?

By counting what is physically there and comparing it with the last count plus deliveries. A bin of empty box tops by the sink tells you what ran out; two numbers per product, station and stockroom, tell you what is about to.

How much back bar should a salon keep on hand?

Work it out per product: how much you use in a day, times the days between deliveries, plus a buffer for late deliveries. Review the number every few months and raise it after any stockout.

How do I know if my salon uses too much back bar?

Compare what left the shelf with the services you did, one product at a time. As an outside check, Strategies puts professional product at 4–6% of service revenue. Working out your own product cost per service is covered in our piece on salon inventory turnover.

Why does product run out mid-service when the stockroom is full?

Because the product is in the wrong place. Track the station and the stockroom as two separate numbers, and restock the station when its number drops.

What should I do with half-used bottles when counting?

Pick one rule and keep it. I count full, unopened units only, because a half-empty bottle gets estimated differently by every person holding it.

How often should back bar be counted?

Weekly for the products you reorder most often and cannot run a service without; monthly for the rest. A fixed day matters more than the exact frequency.

Who should be responsible for ordering back bar?

One named person, on one fixed day, with a deputy for days off. "Whoever notices" is the rule that produces emergency orders.