How to choose a candle wick size
Pick a series for the wax, size it to the diameter, then let a test burn settle it.
The wick is the hardest single variable to get right, because the "correct" wick depends on the wax, the container diameter, the fragrance load, and the dye all at once. The good news: you can get very close on paper, then confirm with one test burn.
Step 1 — pick a wick series for your wax
Wicks come in series (families) tuned to different waxes. You choose a series first, then a size number within it. Common cotton series include ECO, CD, LX, and HTP; wooden wicks are a separate category. Soy and soy-blend container waxes commonly pair with ECO or CD; paraffin and harder blends often use LX or HTP. Start from your wax manufacturer's wick recommendation if they publish one.
Step 2 — size to the container diameter
Within a series, larger wick numbers are rated for larger container diameters. Each manufacturer publishes a chart mapping wick number to a diameter range — that's your starting size. The aim is a wick that melts the wax all the way to the glass:
| Container diameter | Typical starting wick (cotton) |
|---|---|
| ~2 in (5 cm) | small (e.g. ECO 1–2 / CD 4–6) |
| ~2.5–3 in (6–7.5 cm) | medium (e.g. ECO 4–8 / CD 8–12) |
| ~3.5–4 in (9–10 cm) | large (e.g. ECO 10–14 / CD 14–18) |
| > ~4 in (10 cm) | consider multiple wicks |
These are starting points, not final answers — exact numbers differ by manufacturer chart and by wax. Above roughly 4 inches, a single wick usually can't reach the edges, so a double- or triple-wick layout is more reliable than one oversized wick.
A heavy fragrance load and darker dyes both make wax harder to melt, so a candle that tests well plain may tunnel once scented and colored. If you're at a high load or using dark dye, size up one step from the diameter-only recommendation — then verify with a test burn.
Step 3 — read the test burn
Burn a finished candle and watch the first few hours. You're checking the melt pool (the pool of liquid wax) and the flame:
- Full melt pool to the edge in ~2–3 hours, modest flame — the wick is right.
- Tunneling (a ring of unmelted wax left on the glass) — wick is too small; size up.
- Tall, flickering flame, soot, or "mushrooming" (a carbon ball on the tip) — wick is too large; size down.
- Glass too hot to hold — too much heat; size down or split into multiple wicks.
Always trim the wick to about 1/4 in (6 mm) before each burn — an untrimmed wick mimics an oversized one (large flame, soot, mushrooming).
Why a melt pool matters
Container wax has "memory": a candle tends to re-melt only as wide as its first burn. If the first burn tunnels, every later burn tunnels too, wasting wax and drowning the wick. Sizing the wick to reach the glass on that first burn is what prevents it.
Gear this guide uses
Pick a series for your wax, then keep a few sizes around so you can step up or down after a test burn.
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Sources
Wick choice always needs a test burn in your exact wax, vessel, fragrance, and dye; charts only narrow the starting point.