My New Jar Holds the Same 200 g of Wax but Looks Slightly Wider Than the Previous Batch — Should I Measure Internal Diameter Before Using It?

Same fill weight, different shape: what has to give

You weighed 200 g of wax into a jar from the new shipment, the same as always, and it filled to roughly the familiar place. Yet the jar looks a little wider on the shelf. That observation is worth taking seriously, because a fixed weight of the same wax occupies a fixed volume. If the inside of the jar is wider, that volume must spread into a broader, shallower disc. Something about the candle has changed even though the scale reads the same.

There are three possibilities, and they lead to different decisions. The jar may be wider only on the outside, with thicker glass and an unchanged inside. It may be wider inside and shorter inside, so the candle becomes a wider, lower disc. Or your eye may be misled by a different finish, a changed rim or a different lid. Only a caliper separates the three.

The case that matters most for burn performance is the second. A wider, shallower candle presents more surface to the wick and less depth to burn through. The wick you approved was sized for the old proportions, and it now faces a larger circle to melt to the wall.

Yes, measure the inside, and here is exactly what to measure

Measuring internal diameter alone is not enough for this question. Because you are trying to find out where the extra width has gone, you need the inside width, the inside depth and the height at which your 200 g fill actually settles.

Take these readings on your retained jar from the previous batch and on a suggested starting sample of 10 jars from the new one, drawn from different cartons. If the previous batch is gone, measure a finished candle from it you still have; the inside diameter at the top of the wax surface is often easy to read.

Worked example: working out the new fill depth

Say your previous jar measured 62 mm across the inside and your 200 g fill sat 58 mm deep. The new jar measures 66 mm inside. These are illustrative readings of the kind you would take yourself; CSI does not publish internal dimensions.

With the same volume of wax, depth changes with the inverse of the diameter squared. So the new depth is 58 × (62 ÷ 66)², and (62 ÷ 66) = 0.939, which squared is 0.882. That gives 58 × 0.882 = 51.2 mm. The candle is nearly 7 mm shallower.

The melt surface moves the other way. (66 ÷ 62)² = 1.065 × 1.065 = 1.133, so the wick must melt about 13% more surface. A 4 mm change you could barely see from across the room has produced a candle that is 13% broader at the surface and about 12% shallower.

Two practical consequences follow. First, the approved wick may not reach the wall in a sensible time, which shows up as a ring of wax clinging to the glass. Second, if you keep the same wick length, the flame starts from a lower surface relative to the rim, so the visible headspace grows and the finished candle looks under-filled to a customer who knew the old one. Some makers respond by pouring more wax to restore the fill line, which changes the product weight you state on the label and the cost per candle.

Turning the measurements into a goods-in decision

Once you have the readings, the decision is usually clear. Treat the bands below as a suggested starting point for jars in the 6–7 cm range, to be adjusted once your own burn results accumulate.

Sometimes the sample shows a mixture: most jars match the old inside width, and a handful from one carton are wider. That usually points to glass from a different mould or production run packed into the same order. Keep those cartons apart, label them, and either qualify them separately or return them. Mixing both kinds on one pouring line means two slightly different candles leave under one product name, and your burn results only describe one of them.

Any jar in the sample with a chip or a mark that might be a crack comes out of candle production regardless of what the measurements say. Dimensions never override glass integrity.

What to ask the supplier and what to record

If the jars look different from your last order, ask before you pour. For CSI, send a photograph of old and new side by side with your readings on WhatsApp (+91 7397976926) and ask whether the glass or mould has changed. CSI does not publish internal diameters, glass thickness or jar weights, so the answer you receive is information to record, not a specification to rely on. Your own measurements remain the evidence.

In your goods-in record, capture the invoice number, the date received, the listing name exactly as written, the readings from the table above for both jars, your decision, and the name of the person who made it. Keep one unused jar from this shipment as the new reference, labelled with the invoice number, so the next comparison has something physical to measure against.

A final honest note: if the new jar makes a better candle, with a fuller pool and a look customers like, there is nothing wrong with adopting it. Just adopt it on purpose, with a new wick decision and a new fill weight recorded, rather than drifting into it because a carton arrived slightly different.

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