When a candle needs two or three wicks
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Use more than one wick when no single wick in your series can melt the full width of the vessel without a flame that is too tall, smoky or hot. There is no published diameter at which a candle must switch; suppliers instead tell you how to size each wick for a shared vessel. Northwood and NI Candle Supplies both say to divide the vessel's diameter in half and choose each wick from the chart row for that half-diameter. This page explains when a wide vessel calls for two or three wicks, how to size and place them, why wicks set too close together overheat, and how to test a multi-wick candle.
Signs a vessel needs more than one wick
You usually find out in testing. A wide candle needs another wick when you see one of these:
- The largest single wick that burns cleanly still leaves a ring of hard wax at the edge after a full session, and the candle tunnels as it burns down.
- The single wick that does reach the edge burns too tall or too hot. It flickers, smokes, forms heavy carbon, or makes the glass hotter than you would accept. Kohl's protocol 100-Z (February 2025), one published retailer test, sets a maximum flame height of 3 inches and maximum container temperatures of 175°F for glass or ceramic and 140°F for metal [1]; those are one buyer's requirements, not law, but they are a sensible ceiling for your own tests.
- Your vessel is wider than the widest single-wick row on your supplier's chart, or the chart lists a double or triple wick for that diameter.
Some charts make the jump for you, and some do not. Northwood's chart is printed in two pages, smaller containers first and larger containers second, and its large-candle guidance describes double wicking [2]. Where your chart is silent, the test above decides.
The diameter rule you may have read
You may have seen a fixed diameter given online as the point at which a candle needs two wicks. No source was found for any such figure, and none is used here. The width at which one wick stops being enough depends on the wax, fragrance load, wick series and jar, which is why suppliers give a method instead of a number.
Sizing each wick: the half-diameter method
Northwood explains it this way: "Instead of basing the wick size on the total diameter of the container, you need to divide the diameter in half." Its example is a 4 inch soy candle wicked with two LX 10 wicks instead of one LX 24 [2]. NI Candle Supplies gives the same method with a metric example: a 30 cl jar of 77 mm diameter becomes 38.5 mm, and you choose the wick from the chart column for that half-diameter, using the fragranced or unfragranced column as appropriate [3].
Worked through:
- Measure the inside diameter: say 100 mm (about 3.9 inches).
- Divide by two: 50 mm (about 2 inches).
- Look up 50 mm on your supplier's chart in your wax's column. That size is your candidate for each of the two wicks.
- Build the usual test set: the candidate, one size smaller and one larger, each poured as a pair in the same jar.
The method is a starting point, like any chart reading. Two flames in one vessel share and add heat, so the right pair can come out a size smaller than the half-diameter row suggests, or the candle may need a series that burns cooler. Only the test tells you.
Three wicks
None of the sources cited here gives a sizing method for three wicks. One way to adapt the two-wick method, which no source here has tested, is to size each wick for the share of the surface it has to melt, place the three evenly, and test. Treat any three-wick arrangement as untested until you have burned it to the end.
Placing the wicks
NI Candle Supplies says to secure the wicks at equal distances from each other and from the jar's edges, using adjustable wick holders [3]. For two wicks in a round jar, that puts each wick on a line through the center, with the gap between the wicks about equal to the gap from each wick to the glass. For three, set them in a triangle around the center, each the same distance from its neighbors and from the wall.
Keep them straight and fixed while the wax sets, because a wick that drifts toward the glass or toward its neighbor changes the whole burn. Tools for centering and holding several wicks are covered on attaching and centering wicks.
Series that stand straight help. CandleScience reports that its LX wicks stand straight with minimal curl, "making it a good choice for multi-wick candles," and suggests its AL (Aroma-Lite) series for small and multi-wick candles [4].
Why wicks too close together overheat
Each flame heats the wax around it and the air above it. When two flames are close, each one also heats the other: the wax between them melts faster and deeper, the flames can lean toward each other or merge into one larger flame, and more heat goes into the glass nearest them. The result can be a flame taller than either wick would make alone, more soot, and a jar that runs hotter than a single-wick candle of the same size.
That is why spacing matters as much as size: two wicks that would pass evenly spaced can fail when crowded together. If you ever see a flame anywhere other than a wick, crowded wicks and an overheated pool are among the things to check, as covered on secondary ignition, and heat at the glass is one cause of cracked jars, covered on cracked or broken candle jars.
Testing a multi-wick candle
Test it the way you would test any candle, with these additions.
| Check | When | What to look for |
|---|---|---|
| All wicks light and stay lit | Every session | A wick that drowns while the others burn means it is undersized or off position |
| Melt pools join | First and second sessions | The separate pools should meet and reach the glass within the session; a ridge of hard wax between or around them means the wicks are too small or too far apart |
| Flames stay separate | Every hour | Flames that lean together or merge mean the wicks are too close or too large |
| Flame height | Every hour | Within the limit you set; one retailer uses 3 inches [1] |
| Container temperature | Every hour, especially the last third of the candle | Measure the glass nearest the wicks; one retailer's limits are 175°F for glass or ceramic, 140°F for metal [1] |
| Smoke and carbon | Every hour | Heavier than a single-wick candle in the same wax suggests the wicks are oversized for a shared pool |
| Burn to the end | Final sessions | Wicks drifting toward the glass as the wax gets shallow, or the glass getting hotter near the bottom |
How to measure container temperature is on how hot the jar gets, and the full protocol with pass and fail figures is on how to burn test a candle.
Tell customers how to burn it
A multi-wick candle needs all its wicks lit together, every time, so the pools join and the candle burns evenly. Put that in your burn instructions, alongside the trimming and burn-time advice covered on burn instructions to give customers.
Placing the wicks is the next step
Once your test has picked the size and spacing, the practical job is getting every wick into the same place in every jar. Go to attaching and centering wicks for the tools and the method, then test your first batch against the record you made here.
References
- Kohl's, Test Protocol 100-Z: Candle (including freestanding, taper, tealight, votive, filled and novelty candles), revised February 2025, read October 22, 2026. https://link.kohls.com/content/dam/klink/100-Z-CANDLE.pdf
- Northwood, How to Use This Wick Chart (help center article; chart updated November 2023), read October 22, 2026. https://northwood-knowledge.groovehq.com/help/how-to-choose-the-best-wicks
- NI Candle Supplies, The Only Candle Wick Guide You'll Ever Need, June 24, 2025, updated September 17, 2026. https://www.nicandlesupplies.com/blogs/how-to-guides/the-only-candle-wick-guide-youll-ever-need
- CandleScience, Lab Notes: CandleScience Coconut Apricot Wax, undated (images dated April 2024), read October 22, 2026. https://candlescience.com/lab-notes-candlescience-coconut-apricot-wax
