How to Manage Carton, Box, Strip and Unit Medicine Stock

How do you keep carton, box, strip, and unit counts in one number?

Medicine arrives in cartons, is often stored as boxes, and is sold as strips or loose units. If each of those words is its own stock figure, the warehouse and the invoice will disagree by the end of the day. Pick one base unit, usually the smallest unit you sell, and store every quantity in that unit. A carton, a box, and a strip are pack sizes on the product: how many base units sit inside each. The on-hand figure is always base units. “Ten boxes left” is a display for the packer, calculated from that figure, not a second ledger.

Set the pack sizes when you create the product, before the first purchase. Units per strip, strips per box, boxes per carton. Write them down from the physical pack, not from memory of last year’s brand. A wrong pack size makes every later sale look like stock vanished. If a principal changes the pack, treat it as a new setup for new receipts. Do not silently rewrite the conversion on stock you already counted in the old pack.

Purchases then say “three cartons” and the system adds cartons times the pack size to the base quantity. Sales say “four strips” and subtract strips times the pack size. The person at the counter does not do that multiplication on paper. They do need to know which unit they are typing. A sale entered as four cartons when the customer asked for four strips will empty a shelf. The checklist is short: one base unit, pack sizes on the product, purchase and sale both converted through those sizes.

What happens when a purchase includes free strips?

Principals often add free quantity on a scheme. That quantity is still stock. Record it on the purchase so the on-hand figure includes it, and keep it separate from the paid quantity if you need to see the scheme later. If the free strips never hit the stock record, the shelf will show product the system says you do not have, and the next sale will be blocked or will go negative depending on how loose the shop is. Free stock is not a reason to skip the batch and the expiry. Those strips expire on the same rules as the paid ones.

When you sell a full box to a shop, deduct boxes times the units in a box. When you sell one strip from an open box, deduct one strip. Both movements hit the same base quantity, so the remaining strips in the open box and the sealed boxes stay one number. FEFO still chooses which batch that strip comes from. The pack size does not replace the expiry rule. A fresh carton should not be opened while an earlier batch of loose strips is saleable, unless the customer refused that date and the override is on the sale.

How do you check the count is still honest?

Once a week, pick five products that moved. Count one in base units on the shelf, including open boxes, and compare it with the on-hand figure. If it matches, the conversion is doing its job. If it is off by exactly one pack size, someone sold or received in the wrong unit. If it is off by a number that is not a pack, look for a receipt that skipped free quantity or a return that was never posted. Fix the transaction. Do not type a new on-hand number over the top and leave the wrong sale in place, or the next week will be off by the same amount plus the new day’s movement.

The same products are where reorder decisions go wrong. A low-stock warning on base units is useful. A warning that says “one carton” while three open boxes are already on the counter is a display problem, not a buying problem. Buy from the base quantity and the sales rate, after you have looked at expiry. There is no point reordering a product whose short-dated batch has not cleared.

See medicine inventory software and the general version of this problem on stock purchased in boxes and sold in units.

What does the packer see versus the ledger?

The packer thinks in sealed cartons and open boxes. The ledger thinks in base units. Both can be right if the display is calculated and the stored number is not. When someone says “we have two cartons,” ask whether that includes the open box on the counter. If the open box is half sold, “two cartons” will overstate what a full-carton order can take. Train the phrase: sealed cartons for packing, base units for the invoice and the reorder.

A scheme that changes mid-month is a new pack size for new receipts only. Suppose a box that held ten strips now holds twelve. Stock already counted at ten must stay at ten until you recount it. New purchases use twelve. Mixing both in one conversion makes the on-hand figure drift by two strips per box, which looks like theft and is arithmetic. Write the date the pack changed on the product note so the next person does not “fix” it backward.

Returns come back in whatever unit the shop sends. A shop may return three strips from a box you sold as a box. Post the return in strips so the base quantity goes back up by three strips, and put those strips on the same batch they left on if you still know it. Dumping the return into a new batch with no expiry creates a lot that FEFO cannot sort. If you do not know the batch, say so and do not invent a date to make the screen look complete.

Count one open box in strips at the end of the day and compare it with the base units the screen shows for that product. A match means the carton, the box, and the strip are one number. A miss of exactly one pack means a sale used the wrong unit. Fix that sale before you add another conversion “to make it match.”