When Does a Candle Need Two or Three Wicks?

Suppliers point to a jar that is about 3.5 to 4 inches (9 to 10 cm) wide as the place a single wick starts to struggle. Past that, they suggest two or three smaller wicks instead of one big one. Every extra flame adds heat, so a multi-wick candle needs more care, not less. Space the wicks evenly, test in your own jar with your own wax, and never leave a burning candle out of sight.

At what width do I need more than one wick?

The numbers from suppliers are close but not the same:

• CandleScience: multi-wick containers should generally be at least 3.5 inches in diameter, and it starts with doubles before triples. Its support page says a jar 4 inches or wider may not melt a full layer in about 4 hours with one wick.
• CandleScience lab notes: it typically does not recommend multi-wicking under 3.5 inches, because the jar is usually not wide enough to space the wicks from the glass. For one coconut-soy wax it did recommend doubles in jars of 3.3 to 3.79 inches (8.4 to 9.6 cm), after single wicks gave very large flames. That is one wax, one test.
• Lone Star: a jar wider than about 3.5 inches usually needs more than one wick. Its starting rule is one extra wick for every inch past 3 inches: 2 wicks at 4 inches, 3 at 5, 4 at 6. It keeps round jars to three wicks at 4 inches so a fourth flame does not crowd the jar.
• NorthWood: it is very hard to wick containers wider than 3.5 inches, so two or three wicks are often needed.
• Makesy: for vessels over 3.5 inches, consider a larger wick series or a multi-wick setup.

Lone Star also warns that one wick pushed to cover too much can run hot, soot and smoke. Treat all of these as starting points.

How do I size the wicks?

Divide the jar's inside width by the number of wicks, then pick a wick for that smaller section. CandleScience, NorthWood and Makesy all use this method. CandleScience's example: a 4 inch jar with two wicks gives two sections of 2 inches. Lone Star adds a quarter inch (0.25 in, 6 mm) to each section so neighboring pools overlap. Expect smaller wicks than a single wick would need, and "when in doubt, wick down," as CandleScience puts it.

Where do the wicks go?

Evenly. CandleScience says about halfway between the center and the edge, at least 1.5 inches (3.8 cm) apart, and not so near the wall that the flame touches the glass. Its support page says about 1 inch (2.5 cm) between wicks and from each wick to the wall. NorthWood warns that wicks placed too far apart end up too close to the edge, which can overheat the vessel.

Worked example: a 4 inch round jar

Jar width 4 inches (10.2 cm), two wicks. All numbers are examples.

Wick size:

• Method most suppliers use: 4 / 2 = 2.0 inch section
• Lone Star's method: 4 / 2 + 0.25 = 2.25 inches (5.7 cm)
• For three wicks: 4 / 3 = 1.33 inches (3.4 cm), or 1.33 + 0.25 = 1.58 inches (4.0 cm)

You would look up a wick in your supplier's chart for each of those widths, then test.

Placement: the jar radius is 2 inches. Halfway between the center and the edge is 2 / 2 = 1 inch from the center.

• Two wicks on a line through the center: 1 inch each side, so 2 inches apart (passes CandleScience's 1.5 inch minimum)
• Distance from each wick to the wall: 2 - 1 = 1 inch (matches the support page)
• NorthWood's ideal is an equal distance between the wicks and from each wick to the wall: three gaps, so 4 / 3 = 1.33 inches (3.4 cm) each. That is further from the glass but under CandleScience's 1.5 inch minimum, so test the layouts.

Try the same math on a 3.5 inch jar. Halfway is 0.875 inch from the center, so the wicks are 1.75 inches apart and 0.875 inch from the wall. That is under the 1 inch from the support page, which fits the CandleScience lab notes above: a jar this size may not leave enough room from the glass. Burn a single-wick candle next to a double.

What can go wrong?

• More heat. Lone Star says multiple flames put out more heat than one, so check that the glass never gets too hot to handle. Our jar heat guide uses 140 F (60 C) on the outside of the jar as the warning line, the number Armatage and Craftybase use. NorthWood's page gives higher limits, no more than 175 F (79 C) for glass and 150 F (66 C) for tins, and names no source for them. That is one supplier's figure, not permission to run hotter. I found no official number, so stay with the lower line: past 140 F, CandleScience's fix for an over-wicked candle is a smaller wick or fewer wicks.
• Tall, flickering flames. In CandleScience's coconut-soy lab notes, a double CD wick in the large jars gave taller flames that sometimes flickered into the glass, while a double LX kept flames small and tight. Series behave differently.
• Corners. Lone Star says one or two wicks can leave unmelted wax in the corners of a large square jar.
• Fire spacing. Lone Star says to keep a burning test candle at least 12 inches (30 cm) from anything that can catch fire. The National Candle Association gives the same 12 inches, and says to keep multiple candles at least 3 inches (7.6 cm) apart.

Common mistakes

• Using the full jar width to pick each wick, which gives wicks that are too big.
• Placing wicks by eye. CandleScience suggests tracing the jar bottom and marking the spots first.
• Testing one fragrance and assuming the others behave the same. NorthWood says you will probably need separate test candles for each fragrance.
• Leaving a multi-wick test unattended.

Questions

Can I just use one bigger wick in a wide jar?

Lone Star says most wicks top out at a melt pool of about 3 to 3.5 inches, and a few reach about 5 inches but can run hot and soot. Past roughly 4 inches, it says sizing one wick up far enough makes the flame too tall.

What if the pools never meet?

Then the wicks are too small or too far apart, as in our guide on wicks that are too small. Move up one size, or check the spacing, and retest. Do not shift a lit candle's wicks.