Quick Answer: For soy wax in a 3-inch jar, start with a CD 10 or ECO 10 wick. For a 2.5-inch jar, try CD 8 or ECO 8. Always test — these are starting points, not guarantees. The right wick creates a full melt pool in 2-3 hours without smoking.
Why Wick Size Is Critical
The wick is the engine of your candle. Get it wrong, and nothing else matters — the best wax, the finest fragrance, the prettiest jar all fail if the wick is the wrong size.
A properly sized wick:
- Creates a full melt pool (melted wax reaches jar edges) within 2-3 hours
- Burns with a steady, teardrop-shaped flame about 1 inch tall
- Produces minimal soot
- Keeps the jar at a safe temperature (glass should be warm, not hot)
Wick Types for Container Candles
There are many wick types, but three dominate the container candle world:
CD (Stabilo) Series
- Best for: Soy wax, paraffin, and most blends
- Construction: Flat braided cotton with a thin paper thread (filament)
- Why it’s popular: Self-trimming, consistent burn, great with soy wax
- Sizes: CD 1 (smallest) through CD 22 (largest)
CD wicks are the most recommended for soy candle beginners. The paper filament helps the wick curl as it burns, which provides a self-trimming effect and a consistent flame.
ECO Series
- Best for: Soy wax, coconut blends, vegetable waxes
- Construction: Flat braided cotton with thin paper threads
- Why it’s popular: Very clean burn, consistent, designed for natural waxes
- Sizes: ECO 1 through ECO 14
ECO wicks are very similar to CD wicks in performance. Many candle makers use them interchangeably. ECO tends to burn slightly cooler than CD, making it a good choice for fragrances that accelerate burn.
HTP Series
- Best for: Paraffin, soy-paraffin blends
- Construction: Cotton braid with paper core
- Why it’s popular: Good rigidity, works well in wider containers
- Sizes: HTP 41 through HTP 136
HTP wicks are more common in paraffin candles but work in soy too. They have good structural rigidity, meaning they stay upright in deep containers.
Wood wicks
- Best for: Aesthetic appeal (crackling sound)
- Reality check: More finicky than cotton wicks. Harder to size correctly, more sensitive to wax type and fragrance. Not recommended for beginners — learn with cotton first.
Starting Wick Size Chart
Use this as a starting point. You must test — these recommendations get you in the ballpark, not to the finish line.
Soy wax (CD series)
| Jar diameter | Wick size | Notes |
|---|---|---|
| 2 inch | CD 5-6 | Small tins |
| 2.5 inch | CD 7-8 | Small jars |
| 3 inch | CD 10-12 | Standard jars (most common) |
| 3.5 inch | CD 14-16 | Large jars, consider double wick |
| 4+ inch | Double wick | Single wick can’t reach edges |
Soy wax (ECO series)
| Jar diameter | Wick size | Notes |
|---|---|---|
| 2 inch | ECO 2-4 | Small tins |
| 2.5 inch | ECO 6-8 | Small jars |
| 3 inch | ECO 10-12 | Standard jars |
| 3.5 inch | ECO 12-14 | Large jars, consider double wick |
| 4+ inch | Double wick | Single wick can’t reach edges |
Beeswax
Beeswax is denser and has a higher melting point, so it generally needs a slightly larger wick than soy for the same jar:
| Jar diameter | CD wick | Notes |
|---|---|---|
| 2.5 inch | CD 10-12 | Size up from soy recommendation |
| 3 inch | CD 14-16 | May need testing |
How to Test Wicks
Wick testing is non-negotiable if you want consistent, safe candles. Here’s the standard process:
What you need
- 3 candles with the same wax, fragrance, and jar
- 3 different wick sizes (your best guess, one size up, one size down)
- A ruler or caliper
- A timer
- A notebook
The test burn
- Let candles cure — at least 48 hours for soy, ideally 1-2 weeks
- Trim all wicks to exactly 1/4 inch (6mm)
- Burn for 1 hour per inch of diameter — a 3-inch jar burns for 3 hours
- Observe during burn:
- Flame height (ideal: 1-1.5 inches)
- Flame shape (ideal: steady teardrop, no flickering)
- Melt pool diameter (ideal: reaches edges within 2-3 hours)
- Melt pool depth (ideal: 1/4 to 1/2 inch)
- Smoke or soot (ideal: none)
- Mushrooming (small amount is OK, large carbon balls = wick too big)
- After extinguishing:
- Touch the jar — warm is fine, hot means wick too big
- Check melt pool evenness
- Measure any remaining wax wall
Reading the results
Wick too small:
- Melt pool doesn’t reach edges
- Small, weak flame
- Tunneling begins
- Candle takes too long to create melt pool
Wick too big:
- Flame is tall (over 2 inches) and flickering
- Heavy mushrooming
- Jar gets hot to the touch
- Black soot on jar or in air
- Wax burns too fast
Just right:
- Full melt pool in 2-3 hours
- Steady flame about 1 inch tall
- Jar is warm but comfortable to hold
- Minimal to no mushrooming
- Clean burn, no soot
Double Wicking
Jars wider than 3.5 inches usually need two wicks. A single wick simply can’t generate enough heat to melt wax all the way to the edges of a wide container.
Double wick guidelines
- Space wicks evenly — each wick should be centered in its “half” of the jar
- Use wicks 2-3 sizes smaller than what a single wick would need
- Both wicks must be the same size and type
- Test the same way as single wicks — full melt pool, no smoking
When to double wick
- Jar diameter over 3.5 inches
- If the largest single wick still tunnels
- Decorative wide-mouth containers
Factors That Affect Wick Performance
The same wick size doesn’t work for every candle, even in the same jar. These factors change burn behavior:
Fragrance oil
Different fragrances burn differently. Heavy, sweet fragrances (vanilla, caramel) tend to accelerate burning — you might need to wick down. Light, clean fragrances (citrus, linen) often slow burning — you might need to wick up.
Rule of thumb: fragrances with vanillin content tend to burn hotter.
Fragrance load
Higher fragrance percentage = more fuel = hotter burn. If you change your fragrance load from 6% to 10%, you may need to adjust wick size down.
Dye
Candle dye can slightly affect burn. Heavily dyed candles sometimes need a slightly larger wick. The effect is small but measurable.
Wax brand
Even within the same wax type, different brands have slightly different compositions. Golden 464 and EcoSoya CB-Advanced are both “soy wax” but may need different wick sizes.
Jar shape
Tall narrow jars need different wicks than short wide jars, even at the same diameter. Tall jars retain more heat as the flame burns deeper.
Safety Considerations
Wicking is a safety issue, not just a performance one. A wick that’s too large can:
- Overheat the glass, causing it to crack or shatter
- Create a flame that’s too large for the container
- Cause the fragrance oil to ignite
- Produce dangerous amounts of soot
Per ASTM F2417 (the fire safety standard for candles), the flame height should not exceed 3 inches during normal burning conditions. If your candle produces a flame over 2 inches, the wick is too big.
Always test your candles through a full burn — light it and let it burn completely (with supervision) at least once. Some wicking problems only appear when the wax level is low and the jar becomes a heat trap.
Common Wick Mistakes
- Not testing — relying on charts alone without actual burn testing
- Testing too early — testing before the candle has cured (gives misleadingly weak results)
- Not trimming — testing with untrimmed wicks makes every wick seem too big
- Changing multiple variables — test one change at a time. If you change the wick and the fragrance, you won’t know which caused the difference
- Too few test candles — make at least 3 of the same candle. One candle can be an outlier
Use our calculator to get consistent wax and fragrance measurements across all test candles — consistency in materials is essential for meaningful wick tests.
FAQ
What size wick do I need for a 3-inch jar?
For a 3-inch diameter jar with soy wax, start with a CD 10 or ECO 10 wick. This is a starting point — you’ll need to test and possibly adjust up or down based on your specific wax and fragrance combination.
Can I use any wick with soy wax?
Not all wicks work well with soy wax. CD (Stabilo) and ECO series are the most popular for soy. Cotton square braid (HTP) also works. Avoid zinc-core wicks — they’re outdated and unnecessary for container candles.
How do I know if my wick is too big or too small?
Too small: tunneling, weak flame, small melt pool. Too big: tall flickering flame, black smoke, mushrooming, jar gets very hot. The ideal wick creates a full melt pool within 2-3 hours without smoking.
Do I need to wick test every fragrance?
Ideally, yes. Different fragrances affect burn behavior. Vanilla-heavy fragrances tend to accelerate burning, while some florals slow it down. At minimum, test each fragrance family.