How to Track Vending Machine Inventory by Slot

If you only track what you buy from the supplier, you know what you spent. You do not know what each machine sold, which slots are dead, or where product is going bad. Tracking by slot fixes that. It is a bit more work per visit, and it pays off the first time you see that one row of the machine moves three times what the others do.

Start with slot codes

Every machine has a slot (or coil, or spiral) for each product. Most machines label them with a letter for the row and a number for the position, like A1, A2, B1. Use those labels exactly as the machine shows them. If a machine uses numbers only, like 11 and 12, use those.

Your record needs three things to identify a slot: the machine ID, the slot code, and the product. "M03, B4, pretzels" is something you can count and compare next month. "Pretzels at the library" is not.

Write the slot code the same way every time. Pick "A1" and never "a1" or "A-1".

Set a par level for each slot

Par is the number of units a slot should hold when it is full. It is not always the physical maximum. A coil may hold 10 bags of chips, but if the product sells 3 a week and you visit weekly, a par of 6 keeps product fresher and ties up less cash.

Set par from three things:

• How many the slot physically holds.
• How fast it sells between visits.
• How much you are willing to lose if it expires.

Start with full coils, then adjust after a few visits. If a slot is empty every time you arrive, raise par. If it comes back nearly full every time, lower it.

Count what you add, and what was left

The core idea is simple. At each visit, for each slot, you do two counts:

1. What is left in the slot when you arrive.
2. What you add to get it back to par.

The difference tells you what sold since last time. If the slot was at par (say 8) after your last visit, and 5 are left now, then 3 sold. You add 3 to get back to 8. In practice, the number added is the number sold, as long as you always fill to par and nothing else went wrong.

That last part is why you should write down the "left" count, not only the added count. If you only record the add, you cannot tell the difference between a product that sold and one that you moved, tossed, or lost to a jam.

The quick version

If counting every slot is too slow at first, record only the quantity added, always fill to par, and keep your par numbers written down. The quantity added then becomes your sales estimate for that slot. You can add the leftover count later, for the slots you care about most.

Estimating sales from fills

Here is how to estimate sales over a period when you fill to par every time:

• Units sold in a period is about the sum of units added in that period.
• Estimated revenue is units sold times the price in that slot.
• Compare that estimate to cash plus cashless collected for the same period.

Example, with made-up numbers: in a month, slot A1 had 6 + 4 + 5 + 5 = 20 units added, at a $1.75 price. Estimated sales are $35. Do that for all slots, add them up, and compare against the machine's collections.

If the estimate and the real collections are far apart, there is a reason. Common ones are a price in the machine that differs from your notes, product dropped or stolen, free vends or refunds, or a count that was skipped. A gap that is steady each month is a clue, and a gap that jumps around usually points to a missed entry.

This estimate is a check, not a precise count. The real sales number is the money collected. Fills help you see which products make that money.

Spoilage and expiry

Track what you throw out. A line in your notes is enough: "M03, B4, 2 pretzels expired, removed". It matters because spoiled product is a real cost that otherwise hides inside product cost.

A few habits that help:

• Check dates at every visit on anything perishable or close to date.
• Rotate stock so older units go to the front.
• Write the date on cases you open, or the date of the oldest unit in the slot.
• If a slot throws out product more than once, lower the par for that slot or swap the product.

Spoilage shows up in the profit per location math as a cost, so it is worth recording separately from product that sold.

Planogram changes

A planogram is just the map of what product sits in which slot. It changes. You swap a slow candy for a new one, move a bestseller to eye level, or resize a coil.

When a slot changes product, record the change with a date. Otherwise your history for slot B4 will mix two different products and the numbers will not mean anything. Two simple rules:

• Log the date of the change and the new product when you make it.
• Judge a new product after a few visits, not one. Give it enough time to be seen.

Prices can change by slot too. Note the date of any price change, since it affects the sales estimate above.

What to look at once you have the data

• Which slots sell the most units, so you can give them more room.
• Which slots barely move, so you can swap them.
• Which products expire most often.
• Whether sales estimated from fills line up with the money collected.

If you keep this in a spreadsheet, the route spreadsheet guide shows how to set up columns for slot, product and quantity added.

SnackRouteTracker lets you log restocks by product and slot from your phone as you work the machine, then rolls them up into profit per machine. Try it if the counting is getting hard to keep up with.