My Jar Is Wider at the Top than the Bottom — Which Diameter Should I Consider When Planning Wick Tests?

Measure-to-order: three diameters and one weight

Before anything goes in a basket, take four readings from two or three jars of the batch you will actually sell in. Use the inside of the glass, never the outside: a listed or measured outer figure includes two walls (why the external diameter misleads). In a taper the rim is wider again than the fill line, so the rim is the one width that never matters for the wick.

The last reading needs a rule of thumb: wax is lighter than water, and candle makers commonly multiply the water weight by about 0.86–0.9 to estimate wax weight. Confirm with one weighed test pour. In our worked example the taper is even, so the lowest third of the depth holds about 29.8% of the fill: 59.5 g, rounded to a 60 g lower-zone candle. A curved jar can hold much more or much less down there, which is why you weigh it rather than divide by three.

The add-on rule: how much taper earns extra candles

Not every slightly narrower base is worth six more candles. Compare the base pool with the top pool, area to area. The bands below are our judgement, readable off three measurements, and are a buying rule, not a burn prediction.

Our 6.8 cm base is 72.2% of the top, the middle band: six lower-zone candles. If your jar is CSI's Clear Glass Jar with Golden Lid (150 gram), its page lists an outer rim of about 7 cm and a base of about 6.5 cm, both outside figures; on our 0.35 cm wall assumption that is 31.17 against 26.42 cm², 84.8%. That is a hint of a taper, not a measurement: callipers on your own jars decide the band.

Why the top width sets the rungs

A container candle's first burns are commonly expected to reach the glass within about 3–4 hours (a rule of thumb, not CSI data), and a very rough guide is about an hour per 2.5 cm of width: about 3.2 hours at 8.0 cm, about 2.7 at 6.8 cm. If you buy a ladder centred on the base, every rung is sized for a smaller pool than the one your customer lights first, and the likely result is a tunnel at the top that never recovers. If you centre on the middle, you split the difference and test neither end. So the rungs come from the top.

In CSI terms "the rungs" are short: Eco C1, Eco C2 and Cotton Braided Wicks Ready Made, tabbed and ready to use, with no sized, tabbed wick between them and none above Cotton Braided. At an 8.0 cm top with a light herbal oil, our judgement puts the likely answer at C2, with Cotton Braided as the rung that may be needed if C2 leaves wax on the glass. C1 is in the order as the low anchor: it is expected to tunnel at the top, and that documented fail closes the bracket from below. None of that is a verdict; it is why all three are bought.

The oil matters because it sets the likely centre. Eucalyptus Spearmint states "up to 10% for soy wax", so 8% of total weight (which is 8.70% of wax weight) is inside both ceilings: the oil page's and the Chunks page's "up to 13%". Light, bright herbals often burn more easily than dense vanilla or oud oils, a tendency that keeps Cotton Braided at the top of the bracket rather than its centre. CSI has no measured wick data for any oil, so that stays judgement.

One more reason to keep the full ladder: a wick that passes the top and is calm at the base still has to be compared against its neighbours. The bracket logic (a documented fail on each side of the winner) is the same as for a straight jar: the adjacent-rungs post covers what that means with only three rungs.

The lower-zone add-on: how many, how big, what it costs

A lower-zone candle is a shallow pour, in the same jar, of roughly the weight that sits in the lowest third of the fill. Its wick stands on the same base, its pool is the narrow one, and it shows in a session or two what the full candle would show only after days of burning. The method (why the early test looked right, how shallow to pour, how to read it) is the bottom-zone shortcut post; it is labelled there as a screen that never replaces a full life. This page owns the counting.

How many

Three per rung that could win the top, so one odd candle is outvoted. In the middle band that is C2 and Cotton Braided: six candles. C1 is left out because it is expected to fail at the top, and a wick that fails the first burns is not bought however calm it is at the base. If your base is under 70% of the top, add three C1 lower-zone candles too (₹167.87 in materials at ₹55.96 each): in a strong taper the smallest rung is the one most likely to suit the base, and you want that on record.

How big

Weigh it, as above. In the worked example, 60 g at 8% is 4.8 g of oil and 55.2 g of wax. Keep the load identical to the full candles: a lower-zone candle with a different load tests a different candle.

What it costs

That is the whole case for the add-on: it costs about a quarter of the ladder in materials and one bag of wax in cash, and it moves the narrow-base result from the last week of testing to the first.

Why not simply wait for the full candles? Because by the time a full-height candle reaches the narrow base, you have burned it for days, and if the wick runs hot there, the replacement ladder starts from zero. Whether to also carry a lot of the next rung down for exactly that case is the reserve-rung post for narrowing jars.

The whole order, line by line

Everything for the ladder and the lower-zone set, with the smallest in-stock pack that covers each line. The jar is the one item we cannot price: the taper is yours. Load is 8% of total candle weight, CSI's convention.

From nothing, that is ₹2,891.40 in cash plus fifteen jars. The ladder alone would be ₹2,474.40 (two 1 kg bags, two centering packs, the same wicks and oil), so the base set's extra cash is ₹417.00. If you already hold wax and oil, the order is the three wick packs, ₹332.40, and nothing else.

The oil line deserves a check, because it is where baskets usually go wrong. A 100 g + 50 g pair (₹566.40) holds 150 g, short of the 172.8 g needed. Two 100 g bottles hold 200 g and leave 27.2 g: one more 200 g candle (1) or 5 more lower-zone candles, enough to re-pour a split cell. The 500 g is ₹0.24 a gram cheaper but would leave 327.2 g in the cupboard before you know which wick, or which jar, you are keeping.

Notice how little the wick moves the number: the dearest full candle costs ₹6.10 more than the cheapest. The candles are the cost of a test, not the wicks, which is why the add-on is counted in candles.

Reading the two sets, and what each result buys

Pour all fifteen from one pot, the same day, into one jar batch, and cure them identically; the Eucalyptus Spearmint page says "Cure time is 48-72 hours for soy wax", and many makers wait about a week before judging. Then run them in this order.

The second and fourth rows are the reason the lower-zone set exists. Without it, both are discovered in the final third of the ladder, after a week of burning, and the reorder starts from there. How the flame commonly grows in the lower third of a wider jar, and how to separate stored heat from wick size, is the lower-third aggression post.

From an approved wick to a production order

Once all three full-height candles of one rung pass the full life, size the wick order from your own production: wicks = candles × wicks per candle × (1 + allowance), with 5% as our worked-example allowance for rejects and retests. C1, C2 and Cotton Braided are flat per wick, so the pack only changes how much cash leaves today.

A month of wicks is a small line next to the oil and wax; the costly mistake is 150 candles of oil and wax poured around a wick that only passed the top. Reorder points and safety stock follow the hub's formula, daily use × your lead time + safety stock (the hub's production section); CSI dispatches from Pune and publishes no lead times or stock depth, so confirm dispatch on WhatsApp before a large run. What full life costs in days, against what a wrong bulk order costs in rupees, is the heavy-base full-life post.

A change of jar batch is a change of geometry. If a new delivery measures differently at the base, the approval is for the old jar; how small a change still needs a confirmation order is the 5 mm post.

What to buy, and what to skip

Five items in the order the test uses them, chosen on page statements, price and stock on 1 October 2026. CSI publishes no wick-performance data, so nothing is ranked on burn results. Oil candle counts use 16 g per 200 g candle and 12 g per 150 g candle.

Skip for this order: Steel Wick Holder (₹250.00 for 5): a single-wick taper doesn't need a three-hole bar. Eco Candle Wicks Loose: untabbed and described for "2 inch diameters", well below even this base. Performance Wooden Wicks (₹590.00 for 10): one listing with no widths, so it cannot form a ladder; wooden versus cotton is a separate test. Eco Braided Wicks (₹472.00 for 5 m): unsized and cut to length; only worth it if top and base land between CSI's rungs.

Frequently asked questions