In this guide 6 sections
A building supplies catalogue needs one base unit for stock and a defined selling unit for each line, with the conversion between them stored once. Show the price per unit on every line, whether the unit is a piece, a pack, a box or a kilo. Piece prices then stop passing for pack prices.
The units a building supplies shop actually uses
One item can be counted in several ways. A wood screw is a piece, sold in a pack of 100, held in a box of ten packs and bought from the supplier by the carton. Cement is a bag. Rebar is a bar or a bundle. Cable is a metre or a drum.
Each of those is a unit of measure, and each plays one of four roles, which the catalogue must keep apart. Mix them up and the trouble starts.
- Base unit: the smallest thing you count in stock
- Selling unit: what the buyer picks
- Purchase unit: what you order from the supplier
- Display unit: what the product page shows first
How a price per piece gets read as a price per pack
A listing shows a price in large type beside a pack of 100 screws, and the buyer assumes it is the price of the whole pack. If it is the price per piece, the total at checkout is a shock, and the order is abandoned or cancelled. The other way round is worse.
When the figure is the pack price and the buyer reads it as a piece price, a request for 100 screws can arrive as 100 packs. Either error costs a trip. An over-order comes back as part-used packs in a returns queue, and an under-order leaves a crew waiting on site for a second delivery.
Plumbing and electrical lines suffer too. Pipe priced per metre, conduit priced per length and solvent cement priced per tin can sit on one quote, each with a different unit.
Store one base unit and a conversion for each selling unit
Keep stock in the base unit only. Every other unit is a multiplier on it: one pack is 100 pieces, one box is ten packs, and one bundle is a stated number of bars.
When a customer buys three boxes, the system takes 3,000 pieces off the count, and when a supplier delivers by the carton, receiving converts cartons to pieces. Nobody does sums at the counter. That is where slips creep in.
- Unit name and a short code
- Base units contained in one selling unit
- Minimum order quantity and step quantity
- Whether a full pack may be broken and sold loose
- Weight per base unit, for freight and loading
Loose items sold by weight need their own rule
Nails, bolts and washers are often sold by the kilo, so the invoice says kilos, stock says pieces and neither matches the pack the supplier delivered. Record an average weight per piece. Convert with it in both directions.
That piece count is only an estimate. Agree a tolerance with whoever does the stock-take, and count one bin by hand each month to check the average still holds.
Cut-to-length goods such as cable, hose and chain behave the same way, since the roll is stocked in metres and each cut comes off the roll. An offcut below a set length is either written off or kept as a labelled remnant, and the rule should be written down.
A convention for showing the unit on every line
Pick one layout and use it on the product page, the quote, the cart and the invoice: quantity, selling unit, price per that unit, then line total. Add a price per piece beneath. The price per piece is the figure buyers compare between your shop and the next one, so it belongs on the same line as the pack price.
A line might read three boxes, each box ten packs of 100 screws, so 3,000 screws, with the price per box and the price per 100 side by side. The buyer sees the contents before ordering.
Test the layout on someone outside the shop. Show a stranger one product line and ask what a single piece costs, and if they cannot say within a few seconds, rewrite the line.
Unit of measure sheet
One table per product family. Its columns are item, base unit, selling units, base units per selling unit, minimum and step quantity, breakable or not, and weight per base unit. Beneath the table sits a block of five sample lines showing the layout for quantity, unit, price per unit and line total.
Open a blank worksheet to printQuestions owners ask
What is a base unit in inventory?
It is the smallest unit in which a product is counted in stock, such as a piece, a metre or a kilo. Packs, boxes and cartons are multiples of it. Stock stays in one measure.
Should I sell loose fasteners by weight or by piece?
Weight suits bulk bins of small fixings where counting is slow, while piece suits anything a buyer needs an exact number of, such as hinge screws. Store a weight per piece either way.
How do I stop buyers ordering the wrong quantity?
Set the minimum and step quantity to match the pack, put the pack size in the product title, and show the price per piece next to the pack price. The pack is explained before the cart.
Can one product have more than one selling unit?
Yes, cable can be sold per metre and per drum, with the drum defined as a fixed number of metres, and both draw on the same stock. Each unit carries its own price.