A price is a row in a table
A quotation is one row of a comparison, and the unit price is the number in that row. Two suppliers can quote the same unit price and be offering very different purchases, because the price can be built from different light source choices, different battery sizes, different driver schemes and different packaging. The difference is not in the number; it is in what the number was assembled from.
A comparison that holds only the unit price is a comparison of headline figures. It rewards the supplier who has assembled a cheaper unit, and it does not tell the buyer whether the cheaper unit is the one the buyer wants. A comparison that holds the conditions, the documents, the lead time and the defect commitment beside the price is a comparison of the purchases, and it is the comparison a sourcing decision actually needs.
For a buyer the practical rule is that the quotation is answered in the form the buyer wants to compare. A request that asks for the conditions and the documents produces answers that can be put in a table; a request that asks for a price produces a price that cannot be compared with another price without the conditions.
The dimensions that make a quotation comparable
The first dimension is the photometric performance, stated with the conditions behind it. The comparison should hold the total luminous flux with its test machine, the mode and the drive current, the beam angle with its edge definition, the colour temperature with its tolerance and the colour rendering with its method. Each dimension is a row, and each row carries the value and the condition.
The second dimension is the runtime, stated per brightness level. The comparison should hold the runtime at every level with the starting charge, the ambient temperature, the load condition and the cutoff rule. A comparison that holds one runtime figure is holding one level, and the level is a choice the supplier made.
The third dimension is the ingress and weather resistance, stated with its declared test conditions, the materials and finishes, and the drying instructions. A comparison that holds an ingress code without the conditions is holding a claim rather than a property.
The fourth dimension is the battery and its documents. The comparison should hold the cell chemistry, the capacity, the protection scheme, the test summary with its level and validity, and the electrical safety report.
The fifth dimension is the commercial one: the unit price, the tooling, the lead time and the defect commitment. This is the row most buyers read first, and it is the row that is only meaningful beside the others.
The dimensions of a comparable quotation
| Dimension | What the row should hold | What a price alone hides |
|---|---|---|
| Photometric | Flux with conditions, beam angle, colour temperature, colour rendering | Different machines, modes and drive currents |
| Runtime | Runtime per brightness level with charge, ambient, cutoff | One figure describing one level |
| Ingress | Code with declared conditions, materials, drying | A claim without a boundary |
| Battery | Chemistry, capacity, protection, test summary, safety report | A pack without its documents |
| Packaging | Tray, colour box, carton, labels, manual | A change that re-opens the documents |
| Commercial | Unit price, tooling, lead time, defect commitment | The scope of the price |
Ask for the rows, not the price. A comparison built this way is a comparison the buyer can defend, because each row is a question the supplier answered and a document the supplier can produce.
Reading the rows for the differences
The differences that matter are usually in the rows the buyer did not ask about. A lower price with a smaller pack is a lower price with a shorter runtime at the highest level. A lower price with a simpler driver is a lower price with a different end-of-run behaviour. A lower price with a plainer carton is a lower price with a different compliance set. Each of these is a real difference, and each is invisible on the unit price line.
The lead time is a difference of the same kind. A shorter lead time can mean a supplier with spare capacity, or it can mean a supplier who has not qualified the tooling, and the difference is visible only when the tooling row is read beside the lead time row.
The defect commitment is the third difference. A supplier who commits to a rate and can evidence it is offering a different purchase from a supplier who describes quality in general terms, and the difference is visible only when the row is asked for.
The lowest unit price ≠ the lowest total cost
The boundary to state plainly: the lowest unit price is not the lowest total cost. The total cost includes the price of the units, the cost of the documents, the cost of the packaging, the cost of the tooling, the cost of the defects and the cost of the delay, and the lowest unit price can carry the highest total. A buyer who chooses on the unit price alone is choosing on one row and ignoring the others.
A second boundary: a lower price is not automatically a weaker product. A supplier who has assembled a cheaper unit for the same performance has done the engineering, and the buyer should ask where the saving came from rather than assume the product is weaker. The module view is the tool for the question, as set out in camping lantern BOM: LED versus COB.
A third boundary: a higher price is not automatically a better purchase. A supplier who has added a capability the buyer does not need is offering more than the buyer asked for, and the buyer should read the rows and decide which capability is wanted. The discipline that applies to the price applies to the specifications, as set out in the mechanics of spec inflation.
Five questions for the supplier
- Can you quote the photometric performance with the test conditions behind each figure, so the rows can be compared with another supplier? The conditions are the comparison.
- Can you quote the runtime per brightness level with the starting charge and the cutoff rule? A single figure describes one level.
- Can you quote the ingress rating with its declared test conditions and the materials at the joints and the optics? The conditions define the claim.
- Can you quote the tooling, the lead time and the defect commitment as separate rows, and can you state the scope of the unit price? The total cost is more than the unit price.
- Can you send the test summary, the electrical safety report and the market compliance documents with the quotation rather than after the order? The documents are part of the purchase.
Next step
Build the comparison table with the six dimensions, ask every supplier to answer in the same shape, and read the rows rather than the price. Then choose on the total cost and the fit to the use case rather than on the unit price alone. Related reading: camping lantern BOM: LED versus COB fordriver, battery and packaging costlation-mechanics/) for the pressure on the specifications, and RFQ template and golden sample sign-off for the request that produces comparable answers. To apply this to a live sourcing project, start at contact.
Part of the Lumizuno outdoor-lighting notes. Illustrative values only; lumens and ingress ratings must be read with their test conditions.