Candle Wick Sizes Explained: What the Numbers Really Mean (CD, ECO, LX, HTP)

A question we get a lot is some version of this: "Is it normal for a CD 16 to burn hotter than a CD 18? It looks like the smaller number is actually burning bigger." The short answer is that wick numbers only tell you relative size inside one series, and even then the number is a starting point, not a promise. Inside the CD family a CD 18 is a bigger wick than a CD 16, so if your 16 looks like it is out-burning your 18, the two candles almost certainly are not as identical as you think.

My husband Chad and I burned through a frustrating amount of wax learning this when we started Garsnett Beacon Candle Co. at our kitchen table, so let me break down what wick numbers actually mean and why two wicks that should behave a certain way sometimes don't. If you want the full testing method behind all of this, we go deep in our field guide to choosing a candle wick.

What candle wick numbers actually mean

Every wick series has its own numbering, and the number is just a size label inside that one family. Bigger number, bigger wick, built to pull more fuel and throw a wider melt pool. That holds for CD, ECO, LX, and most others. The trap is assuming the number means the same thing across series. It does not.

Here is a quick rundown of the series most makers reach for:

• CD and CDN: coreless cotton with paper threads woven in. They curl as they burn, which helps them self-trim and stay cleaner. Great for soy, coconut, and natural blends. CDN is the same idea with a stiffer curl. Numbers run small to large, roughly CD 2 up to CD 22.
• ECO: flat coreless cotton with a thin paper filament, built to curl and burn clean in soy and natural waxes. An ECO 10 is nowhere near the size of a CD 10, so you cannot swap them one for one.
• LX: flat braided cotton with a stable, mostly upright flame. Makers like it in soy and paraffin blends when they want a steadier look.
• HTP: cotton with paper for a hotter, self-trimming burn, popular in soy and paraffin. Heads up: the HTP numbers jump around (31, 41, 52, 62, 73), so they are not a neat 1, 2, 3 ladder.

The takeaway: a CD 16, an ECO 16, and an LX 16 are three completely different wicks. The only time the number helps you is when you are comparing two wicks in the same series.

So why is my smaller wick burning hotter?

If a CD 16 really is out-burning a CD 18 in your candles, the number is not broken. Something else in the two candles is different. Here is what Chad and I check first:

1. Different fragrance oils. This is the number one cause. Some oils are thirsty and feed a bigger, hotter flame. Others are heavy and partially choke the wick. If your 16 candle and your 18 candle have different scents, you are not testing wick size at all. You are testing two different recipes.
2. Fragrance load. Even the same oil at a different percentage changes the burn. Remember to calculate your fragrance oil as a percentage of the total candle weight, not the wax alone, so you are comparing real numbers. We walk through this in candle math made simple.
3. Dye and pigment. Color, especially heavier pigments and some dye blocks, can slow or clog a wick. A dyed candle and an undyed one will not burn the same even with the identical wick.
4. Cure time. A candle that cured ten days and one that cured two days throw and burn differently. Compare them at the same age.
5. Where you are in the burn. A fresh light looks small. Three hours in, the melt pool is wide and the flame is taller. If you lit them at different times, you are comparing two different moments.
6. Centering and drafts. An off-center wick, or a vent, fan, or doorway draft, will make one candle look wild and the other look tame.

Once in a while it really is the wick, like a miscut or a mislabeled spool. But that is rare. Nine times out of ten it is one of the six things above.

How to actually compare two wicks

The only way to trust a wick result is a clean side-by-side. Pour both candles with the same wax, same fragrance, same fragrance load, same dye (or no dye at all), and the same vessel, then let them cure the same number of days. Label the bottom of each one with the wick size. Burn them in the same room, at the same time, for the same length of time, and watch what happens.

We log every one of these tests in Makers Manager, the software Chad and I helped build so we could stop keeping burn tests on sticky notes. You can track the wick, wax, fragrance, melt pool, and flame notes for each test and actually see which combo won. If you want to try it, the code CBP7DAYS at checkout gives you 7 days free.

Here is what we watch for during the burn:

• A full melt pool (liquid wax edge to edge) within about 2 to 4 hours, without a thick wall of leftover wax clinging to the glass.
• A flame around 1 to 1.5 inches, steady rather than towering or flickering hard.
• Little to no mushrooming, soot, or black carbon tips.
• A vessel that gets warm but not so hot you cannot pick it up.

If the smaller wick hits all of that and the bigger one is tunneling or drowning itself out, then for that specific recipe the smaller wick is your winner. The number lost to the real-world test, and that is exactly how it is supposed to work. If neither wick can reach the edges of a wide vessel, that is usually a sign to size up or look at running more than one wick. And if your winning wick is burning too hot or tunneling, our guide to common candle problems and how to fix them walks through the fixes.

A few quick questions we hear

Does a higher wick number always burn hotter?

Inside one series, a higher number is a bigger wick and usually a bigger, hotter burn. Across series the number means nothing, and within your specific candle the wax, fragrance, and dye can flip the result entirely.

Can I swap a CD for an ECO at the same number?

No. The series are built differently and the numbers do not line up. If you change series, you retest from scratch. Treat it like a brand new candle.

Why does the same wick burn differently with a different scent?

Fragrance oils have different chemistry and weight. One oil can feed a clean, tall flame while another slows the fuel down and makes the same wick look weak. That is why we test every new fragrance as if it were a completely new candle.

Don't overthink the number

Wick numbers are a helpful shortcut for ordering a range to test, and that is about it. They point you to a starting size inside a single series. The candle in front of you, with its exact wax, fragrance, load, and color, gets the final vote. When something looks backwards, trust a clean side-by-side test over the label on the spool every time. Grab our supply checklist if you are still building out your testing kit, and come share your results with us in the free Candle Business PRO Facebook group. We love seeing these burn tests.