Guide
How to choose the right candle wick size
Start with your wick supplier's chart: find your wax, then your container's diameter, and pick the suggested size. Then burn-test that wick and the sizes either side of it. No chart can account for your exact jar, fragrance and dye, so the burn test is what decides.
What a well-wicked container candle looks like
After 3 to 4 hours of burning, a correctly wicked candle has:
- A steady flame about 1 inch (2.5 cm) tall that doesn't flicker or smoke.
- A melt pool that reaches the edge of the jar.
- A melt pool about ¼ to ¾ inch (6 to 19 mm) deep.
- No soot on the glass, and clean sides once the candle has burned down.
Step 1: Measure the container's diameter
Measure across the inside of the jar at the top of the wax line. For tapered or curved jars, measure at the widest point the wax will reach. Wick charts are organised by this diameter, usually in inches.
Very wide containers often need two or three wicks, because a single wick can't melt wax all the way to the edge without burning too hot in the middle.
Step 2: Pick the wick series for your wax
Wicks come in series designed for different waxes. Some are made for soft natural waxes such as soy, and others for paraffin. Your wax supplier usually recommends a series. Choose one series and stay with it while testing, so you only change one variable: the size.
Step 3: Adjust for fragrance and dye
Fragrance oil and dye change how a candle burns. A common adjustment is to go up one or two wick sizes for heavy fragrance loads (more than about 1 oz per pound of wax, roughly 6%), dense fragrances or dark dyes. Go down one or two sizes for light fragrance loads or undyed candles.
Step 4: Run a burn test
- Pour two or three test candles in the same jar, wax and fragrance, each with a different wick size from the same series. Label each one.
- Let them cure. Wait at least 24 hours, and ideally the full cure time for your wax. See how long to cure candles.
- Trim the wicks to about ¼ inch, place the candles well apart away from drafts, and light them at the same time.
- Burn for 3 to 4 hours, then check flame height, melt pool width and depth, and any soot.
- Let them cool completely and repeat for several cycles. A wick that looks right on the first burn can run too hot further down the jar.
Never leave a burning test candle unattended, and keep notes for each cycle so you can compare sizes fairly.
Reading the results
| What you see | Likely cause | Try |
|---|---|---|
| Melt pool doesn't reach the edge after 3–4 hours | Wick too small | Next size up |
| Tunnel forming down the middle | Wick too small | Next size up |
| Weak, small flame | Wick too small or trimmed too short | Leave a little more wick, then size up |
| Tall or flickering flame | Wick too large | Trim shorter, then size down |
| Black soot on the glass | Wick too large, or too much fragrance | Size down or lower the fragrance load |
| Melt pool deeper than about ¾ inch | Wick too large | Next size down |
| Jar gets very hot to the touch | Wick too large | Next size down |
If wax is still clinging to the sides after the first one or two burns, keep testing. Early burns lose heat from the top of the jar, and later burns often melt more of the edge. A thin layer, about ⅛ inch or less, is normal early on.
When to retest
Change any one of these and the wick may need to change too: the jar, the wax, the fragrance oil, the fragrance load or the dye. A new fragrance in an existing recipe deserves at least one test candle before you sell it.
Plan your test batch. Use the wax & fragrance calculator to work out exactly how much wax and oil each test candle needs.