A New Supplier Is 15% Cheaper Than My Existing Supplier — How Do I Calculate Whether the Savings Justify Qualification Testing and Potential Production Variation?

Turn "15% cheaper" into rupees per candle

A price difference on a quote is a percentage of the raw material. Your business earns or loses money per finished candle. So the first job is to translate your 15% — your figure, from your two quotes — into what it saves on one candle, then on a year of candles, and only then weigh it against what qualifying the new supplier will cost.

For a worked example, treat Luxury Soy Wax CSI 464 as your existing supplier's price. The 10 kg pack is ₹5,074.00, which is ₹5,074.00 ÷ 10 = ₹507.40 per kg. A supplier 15% cheaper would charge, hypothetically, ₹507.40 × 0.85 = ₹431.29 per kg. The saving is ₹507.40 − ₹431.29 = ₹76.11 per kg.

At this series' convention of a 200 g candle at 8% load, each candle holds 184 g of wax. The saving per candle is 0.184 × ₹76.11 = ₹14.00. That is real money. Now see how it sits inside the whole candle.

The 15% on wax becomes ₹14.00 ÷ ₹253.60 = about 5.5% of your candle's material cost. Still worth having. But it is a third of the headline, and it is the number every other cost in this decision has to be weighed against.

What qualification actually costs

You cannot swap wax suppliers without testing. A new wax can need a different wick, give a different surface, or throw fragrance differently, even when both products are sold as soy container wax. The minimum sensible qualification is a controlled comparison: candles made from the new wax and candles from your current wax, same jar, same wick, same oil and load, same pour temperature, same cure, same room, burned side by side.

Here is an illustrative qualification bill, assuming you buy a 10 kg trial from the new supplier and make 12 test candles on the new wax plus 8 controls on the wax you already have:

At ₹14.00 saved per candle, the qualification pays for itself after ₹8,466.90 ÷ ₹14.00 = 605 candles, rounded up. At 400 candles a month, that is about six weeks. And the arithmetic is kinder than it looks, because most of the trial wax and the unused oil carry forward into production if the new wax passes.

The cost you cannot see on the quote: variation

The larger risk is not the qualification. It is what happens after you switch if the new supplier's wax varies more from lot to lot than your existing one. Variation shows up as cosmetic rejects, candles you have to re-wick, or customer returns — and every rejected candle throws away all its materials, not just the wax.

A rejected candle made on the cheaper wax loses ₹239.60 of materials. So the saving vanishes once extra rejects reach ₹14.00 ÷ ₹239.60 = 5.8% of production. If you honestly expect the new supplier to cause, say, 3% more rejects than your current one, the expected loss is 0.03 × ₹239.60 = ₹7.19 per candle made, and the net saving drops to ₹14.00 − ₹7.19 = ₹6.81 per candle.

You do not know the new supplier's reject rate in advance, and that is the point. The qualification trial tells you whether one lot works. Only several deliveries tell you whether the supplier is consistent. That is why a sensible switch is staged: qualify, run a pilot, then track rejects per delivery for the first few lots before moving your whole volume.

What to record so the decision survives scrutiny

A cost comparison is only as good as the records behind it. Before the trial starts, set up a simple sheet with one row per test candle: candle number, wax source, your own lot code for that wax, jar, wick, oil and load, pour temperature, pour date, cure length, and then the burn observations. Write the lot code even for your current wax, because a control made from an odd lot of your existing supplier's wax would flatter the newcomer.

During the burns, record the same things for every candle at the same points: melt pool at the end of each burn session, flame height by eye against a simple ruled card behind the jar, any soot or mushrooming, and hot throw scored blind by someone who does not know which candle is which. Photograph the tops after cooling. None of this needs lab equipment; it needs consistency.

After you switch, keep one more column running: rejects per delivery. A single number per lot — candles made, candles rejected, reason — is enough to test the assumption you made in the sensitivity table. If the real figure stays low for several deliveries, your saving is confirmed. If it creeps up, you will see it within a lot or two rather than at the end of the year.

A decision rule you can defend

Put the whole comparison on one line. Annual saving, from your volume and the per-candle saving. Minus qualification cost, one-off. Minus expected extra rejects, estimated honestly and then checked against real delivery records. If the result is clearly positive after a pilot and the first few deliveries, the switch is justified. If it depends on an optimistic reject assumption, it is not yet justified — keep testing or keep your current supplier.

Two further questions belong in the decision. First, what does the new supplier tell you about lot identification and technical support? Ask for lot numbers and any certificate of analysis they offer, and record the answer. CSI's own product pages do not publish these, so the same question applies to us. Second, what happens if the new supplier runs short? Switching your whole volume to one untested source removes your fallback.

And an honest note from a supplier. If you are the reader whose existing supplier is CSI and someone offers you wax 15% cheaper, run exactly this calculation. If the numbers and the trial favour them, that is a sound decision. If you are switching to us from someone else, the same rules apply: our wax earns its place through your comparison, not our price list.

Where this page fits

CSI already has guides that cover parts of this question. This page covers the goods-in check for the question above; these go deeper on the rest:

Three things to buy for this job

Frequently asked questions