The short answer
Choose a candle wick by the wax product and the inside width of your round container, using a chart published for that exact wax as your starting point. Make comparable testers with nearby wick sizes in the same series and burn each through its useful life. A narrow persistent pool points toward an undersized wick; a tall, sooty flame or very hot jar points toward an oversized one.
Start with the wax and the jar, not a universal chart
A wick is the fuel delivery system. Melted wax travels through it to feed the flame. A jar with a wider inside diameter asks the flame to heat more wax; a different wax can change how that heat moves. Published wick charts ask for the wax product and the container diameter, then suggest a size to test. Suppliers treat the chart as a starting point, because fragrance and dye change the result.
Measure the inside diameter where the candle burns. Use the wax product name rather than only “soy” or “coconut.” Two products in the same broad family can have different published wick guidance. If your exact wax has no chart, do not borrow another wax’s size and call it a recommendation. Begin with a small, documented test set from the wax maker’s own advice, and record the uncertainty.
| Know this before choosing | Why it matters |
|---|---|
| Exact wax product | A wax-family label hides product-level differences |
| Inside width and container shape | Width changes the area the flame must heat; CandleEasy’s placement tool covers round containers |
| Fragrance and load | The finished formula can burn differently from an unscented chart test |
| Dye and any additives | A change may shift flame and soot behavior |
| Wick series and size | Sizes are ordered within a series; numbers from different series are not comparable |
Free tool
Find published cotton-wick starting points for a listed exact wax and round jar, then test your finished formula.
Read wick series and sizes correctly
A series is a family of wick construction, such as CD, ECO or LX. Within a series, a higher number is a larger wick. A published guide is explicit that an LX number cannot be compared directly with an ECO number. Test adjacent sizes within one series first; changing both series and size at the same time makes the result hard to interpret.
Wood wicks require their own product-specific sizing and are outside CandleEasy’s Wick Calculator. A cotton size cannot be translated into a wood width or thickness. Read the wood-wick guide and the wood-wick maker’s chart if you choose that material.
The Wick Calculator can give a published starting set for a listed exact wax and round jar, including a placement guide where applicable. If it has no published chart for your wax or diameter, it says so. Its output is a test plan, not a promise about your finished candle.
How a burn tells you to wick up or down
| Repeated observation | Possible interpretation | Next check |
|---|---|---|
| Pool remains well short of the wall; flame weak | Wick may be too small | Confirm a full burn cycle, then test the next size up |
| Tall flickering flame, deep pool, frequent soot | Wick may be too large or formula too heavily fueled | Test a smaller size and review fragrance and dye |
| Wax on walls in early cycles only | May clear as the flame moves lower | Keep testing rather than judging the first burn |
| Jar becomes unusually hot or cracks | Hazard, regardless of pool width | Stop; review the wick and container |
One supplier’s guide advises judging the melt pool, flame and soot together. It notes that an early thin film on a jar wall can disappear in later burns, while a persistent ring after the fourth cycle can indicate an undersized wick. Its example of over-wicking includes a flame that keeps flickering, a pool deeper than about half an inch, carbon buildup, soot and a container that gets very hot. Use those as warning signs, not as a substitute for your vessel maker’s instructions.
Watch the whole candle
A wick can look good near the top yet make the lower jar too hot. Burn test through the candle’s useful life, stay nearby while it is lit, and stop if the vessel or flame behaves dangerously.
Make your next test useful
- Pick a chart for your exact wax and container when one exists. Write down its publisher and suggested wick series.
- Pour testers that share the same batch, jar, fragrance load and dye; vary only the wick size.
- Label each size and run a full burn test, recording each cycle.
- If the wick is too small or large, change one size within the series and pour a new tester. Do not switch a wick halfway through a used candle.
- If you change wax, oil, load, dye or jar later, test the changed formula again.
One “winning” size is not automatically portable to a different scent. A wick is chosen for the finished candle. Save the exact combination that worked, the conditions under which you tested it, and the observations that made you choose it.
Common questions
What size wick do I need for a 3-inch jar?
The jar width alone cannot name a dependable wick. Choose a chart for your exact wax product, then burn test its suggested size with your fragrance and dye. Different waxes can need different wicks in the same jar.
Can I compare ECO and CD wick numbers?
No. Numbering orders sizes within a particular series; it does not create a scale shared across wick series.
Should the melt pool reach the wall on the first burn?
Do not decide from the first burn alone. A small amount of wall wax can clear in later burns. Assess repeated cycles and stop immediately for overheating or other hazards.
Can I use this cotton chart for a wood wick?
No. A wood wick has its own construction and product-specific sizing instructions. CandleEasy’s Wick Calculator does not recommend wood wicks.
Sources
- Choosing the Right Wick Size — CandleScience
- Wicking Container Candles — CandleScience
- How To Conduct a Basic Burn Test — CandleScience
Updated October 5, 2026. These guides are starting points — always burn test your own candles.