Selling by the metre, litre or hour: part quantities explained
Why cable, sealant and labour need stock and quotes that handle part quantities, and what quietly goes wrong when they don't.
By The Osmuch team · · 4 min read
In short
- Plenty of what a trade sells does not come in whole units: cable, pipe, sealant, labour.
- A system that only holds whole numbers rounds 2.5 to 3, silently, on the price and on the shelf.
- Stock things in the unit you sell them in, even if you buy them in drums or boxes.
- Some things must stay whole: anything with a serial number is one physical item.
A plumber sells pipe by the metre. An electrician sells cable by the metre and labour by the half hour. A decorator sells paint by the litre. Much of what a trade business sells does not come in whole units, and a stock or quoting system that assumes it does will get the numbers wrong in a way that is easy to miss.
What goes wrong with whole numbers
Many systems store quantities as whole numbers. Type 2.5 and the database quietly keeps 3. On a quote, two and a half hours of labour becomes three, and the customer is charged for half an hour nobody worked. On the shelf, 12.5 metres of cable leaves as 13, and after a few months the stock figure is metres out with no single entry to blame.
The worst part is that nothing looks wrong at the time. The screen shows 2.5 while you type. The rounding only appears later, on the invoice or at the stock take.
Choose the unit you sell in
Keep stock in the unit you sell or use it in, not the unit you buy it in. If cable comes in 100 metre drums, book a drum in as 100 metres. If sealant comes in boxes of twelve tubes and you use it by the tube, stock tubes. Converting at the point of delivery once is far easier than converting every time something goes out.
What should stay whole
Some things only exist as whole units. A boiler with a serial number is one boiler; there is no half of it. Anything you track by serial number should always be counted in whole units, and so should anything drawn from a numbered batch that you count item by item.
Labour is a quantity too
Labour priced by the hour is a quantity like any other, and half an hour is a normal thing to quote. Labour should also stay off the documents that are about physical stock: a picking slip that lists "Electrician, 6 hours" sends somebody looking for something that is not on a shelf.
Questions
Can I quote half an hour of labour?
You should be able to. A quote for 2.5 hours should charge for 2.5 hours, and the invoice should say the same. If your system turns it into 3, it is rounding your quantities.
What unit should I stock cable in?
The unit you sell it in, usually metres. Book a 100 metre drum in as 100 metres when it arrives.
Doing this in Osmuch
Osmuch keeps quantities to three decimal places, on stock and on every quote, project and invoice line, so 2.5 hours stays 2.5 hours from the quote through to the invoice, and 12.75 metres of cable comes off the shelf as 12.75. Lines marked as labour stay off picking and delivery slips. Products tracked by serial number or batch are counted in whole units, because one serial number names one thing.
Guide: adding your first product · Guide: building and sending a quote · Guide: barcodes batches and serials