How to Choose a Candle Wick: Series, Size and Test Burns

The wick is the engine of your candle. You can have great wax and a gorgeous fragrance oil, but if the wick is too small the candle will tunnel and drown itself, and if it's too big it will smoke, overheat the jar and burn off the scent before it ever fills the room. The good news: picking a wick isn't guesswork. It comes down to a handful of variables you can control. In this guide we walk you through how we balance them and, more importantly, how to confirm your choice with a real test burn. If you want to browse specific products, everything is in our candle wick section.

What a wick actually does

The flame doesn't burn the wick, it burns the wax. Heat melts the wax around the wick, the wick draws that liquid wax up by capillary action like a sponge, and at the top the wax vaporizes and burns. That's why wick size controls how much fuel gets "pumped" per minute, which in turn sets the flame height, the width of the melt pool and how hot the container gets.

When you choose a wick you're looking for balance: a steady flame that melts the whole surface edge to edge in a reasonable time, with no smoke, no oversized carbon "mushroom" and no dangerously hot jar. Everything else (wick series, thickness, number of wicks) is just a tool to get you there.

The most common wick series

Wicks are grouped into series based on how they're braided and whether they include paper threads or other reinforcement. Each series has its own numbering, and those numbers don't translate between series: a CD 10 is not the same as an ECO 10. Within one series, a higher number means a thicker wick and a bigger flame.

Series	Construction	Best-matched waxes	Strengths
ECO	Flat cotton with thin paper threads	Soy, rapeseed, coconut, natural blends	Stable flame, minimal mushrooming, beginner-friendly
CD	Flat cotton with interwoven paper threads	Soy, paraffin, viscous waxes	Self-trimming, handles heavy fragrance oils
HTP	Flat cotton with paper filaments, tighter braid	Viscous natural waxes, paraffin, pillars	Hot flame, melts stubborn waxes well
LX	Flat braid with stabilizing threads, no paper	Paraffin, blends, soy container candles	Curls and self-trims, very little soot
Wood	Wood strip, single or layered ("booster")	Coconut, soy, soft blends	Crackle, wide flame, looks great
Square-braid cotton	Round or square braid of pure cotton	Beeswax, pillars and tapers	Stiff, ideal for hard waxes and freestanding candles

For a first soy candle in a jar, ECO wicks are the most forgiving: they tolerate small mistakes and barely mushroom. If you're working with a thick wax or a high fragrance load, CD wicks and HTP wicks have more pull. Wood wicks are their own world: they need a free-flowing wax and a very short trim, but the result is stunning.

Container diameter comes first

The single biggest factor is the inside diameter of the jar or candle, measured at the opening (or at the widest point if the vessel flares out). The wick has to melt all the way to the edge; otherwise the candle starts tunneling from the very first burn. As a general starting point:

Inside diameter	Typical approach
Under 2 in (5 cm)	One wick from the small end of the series
2–3 in (5–7.5 cm)	One small or medium wick
3–3.5 in (7.5–9 cm)	One medium or large wick
3.5–4 in (9–10 cm)	One large wick or two small wicks
Over 4 in (10 cm)	Two or three wicks

Treat this as a starting point, not a recipe. The manufacturer's wick chart, our wick size calculator and your own test burn get the final say. Watch the height, too: in very tall jars the flame gets less oxygen as it burns down, so it often pays to start one size up; in short, wide tins the flame tends to run bigger.

Wax type changes the size

Every wax has its own viscosity and melt point, and that affects how easily it travels up the wick:

• Soy and rapeseed: thicker when melted, they usually need a wick one size larger than paraffin in the same jar.
• Coconut and coconut blends: very free-flowing and quick to melt; a smaller wick is often enough.
• Beeswax: dense with a high melt point; it needs heavy square-braid cotton wicks, usually several sizes above what you'd use for soy.
• Paraffin: burns easily and works with nearly every series; it's the most forgiving.

Still deciding on a wax? Read our guide to choosing the best candle wax before you buy wicks, because switching waxes almost always means testing again.

Fragrance, dye and additives

Whatever you add to the wax travels up the wick too. A high fragrance load, especially with heavy oils (vanillas, ambers, woods), can clog the wick and push you up a size. Some very light oils do the opposite and enlarge the flame. Always stay at or below the maximum load on your supplier's data sheet and check their IFRA certificate; there's more on that in our fragrance load guide.

Too much color, especially pigments and mica, can clog the wick and cause small, sputtering flames. Use dyes made for candles at the lowest dose that gives you the shade you want, and keep mica out of the wax of any candle meant to burn. Additives like stearic acid or Vybar change burn behavior as well: any change to the recipe is a reason to test again.

When to use two or more wicks

Once you pass roughly 3.5–4 in (9–10 cm) in diameter, a single wick usually falls short, or, if you size it up a lot, gives you a tall, unstable flame. Two smaller wicks spread the heat and build a more even melt pool. A few rules of thumb:

• Place the wicks at equal distances from the center and from the wall; a wick centering tool saves you a lot of grief.
• With a double wick, drop one or two sizes compared to a single wick: the flames heat each other.
• Make sure the two flames don't merge or lean toward each other; if they do, they're too close together or too large.
• In thick ceramic or concrete vessels, which soak up heat, a double wick helps the melt pool reach the edge.

How to run a real test burn

No chart replaces a test burn. Do it with a fully cured candle (at least a few days; ideally one to two weeks for natural waxes), always supervised, on a heat-resistant surface and away from drafts.

1. Pour several versions: the same recipe with two or three wick sizes. Label them.
2. Trim the wick to about 1/4 in (5–6 mm) before lighting.
3. First burn: let it burn until the melt pool reaches the edge. A handy rule is about one hour per inch of diameter, never more than 4 hours.
4. Check every hour: flame height and steadiness, smoke, mushrooming, melt pool depth and jar temperature (touch the side carefully).
5. Extinguish, let it cool completely and repeat burns all the way to the bottom. A wick that's perfect at the top can struggle halfway down or near the base.

How to read the melt pool

• Full melt pool within 3–4 hours, about 1/4–1/2 in (0.6–1.3 cm) deep: right wick.
• Melt pool doesn't reach the edge or leaves a wall of wax: wick too small; go up a size.
• Very deep pool (over about 3/4 in / 2 cm), tall flame, smoke or a very hot jar: wick too big; go down a size.
• Flickering flame that drowns: wick too small, or clogged by fragrance or dye.

If something goes wrong (tunneling, soot, sinkholes), our candle troubleshooting guide covers the most common causes and fixes.

Trimming and wick care

Even the right wick needs a little care. Before every burn, trim it to about 1/4 in (5–6 mm); wood wicks shorter, roughly 1/8–3/16 in (3–5 mm). That keeps the flame in check and prevents black smoke and soot rings on the glass. A wick trimmer reaches the bottom of tall jars easily, and removing the charred bits keeps them from falling into the wax.

Stick to the basics: never leave a burning candle unattended, don't burn it for more than 4 hours at a time and put it out when about 1/2 in (1–1.5 cm) of wax remains. With the right wick and these habits, your candles will burn clean and throw scent the way they should.

Most popular projects