How to Choose the Right Wick for Your Candle

Choosing the right wick is one of the most important parts of candle making. A wick that is too small may struggle to create an effective melt pool, while a wick that is too large can create excessive heat, a large flame or soot. The right candle wick is not determined by wick size alone: it is selected for the complete candle formula, including the vessel, wax, fragrance and fragrance concentration.

If you are building your candle formula, explore our candle making supplies, candle waxes and fragrance oils.

What does a candle wick do?

A candle wick transports liquid wax to the flame. When the candle burns, heat melts the wax around the wick. The liquid wax is drawn upwards through the wick and converted into vapour, which burns at the top of the wick.

This means the wick is an essential part of the candle's fuel system. Its construction and size influence flame behaviour, melt-pool development and burn rate.

Start with your candle vessel

For container candles, the internal diameter of the vessel is one of the most useful starting points for wick selection. A wider vessel generally requires a different wick solution from a narrow vessel because the heat needs to reach a larger area.

Measure the internal diameter of the vessel rather than relying on the outside measurement. Then use the wick manufacturer's recommendations for your chosen wax and wick family as a starting point.

Wick size is not universal

There is no single wick size that works for every candle. Wick numbering and sizing systems vary between manufacturers and wick families, so comparing numbers from different ranges can be misleading.

For this reason, always use the manufacturer's own wick chart or recommendations where available. If you change wick family, treat it as a new test rather than assuming a similar-looking wick will perform in the same way.

How wax affects wick choice

Wax has a major influence on wick performance. Soy, paraffin, beeswax and blended waxes have different characteristics, and even two products within the same wax category can behave differently.

If you change your wax, you should reassess the wick. The same applies if you significantly change your fragrance concentration or other parts of the formulation.

For more guidance, read our guide on how to choose the right wax for candle making.

How fragrance oil affects wick performance

Fragrance oil is another important variable. Different fragrance oils can have different physical properties and can interact with the wax in different ways. Fragrance concentration can also affect how the candle burns.

This is why testing an empty or unscented candle is not enough when you are developing a scented product. The final wick should be tested in the actual fragrance formulation.

If you are comparing scent materials, read our guide on fragrance oil vs essential oil for candle making.

How to choose a starting wick

Start with the wick supplier's recommendations for your vessel diameter and wax. Where appropriate, test a small range of nearby wick sizes rather than relying on a single option. This gives you a comparison and helps identify whether the candle is being under-wicked or over-wicked.

Signs a wick may be too small

A wick that is too small may struggle to maintain a suitable melt pool, may tunnel or may produce a flame that is consistently weak for the candle design. However, these symptoms can have more than one cause, so always consider the complete formulation.

Signs a wick may be too large

A wick that is too large may create a flame that is unnecessarily large, excessive heat, soot or smoke, rapid consumption of wax or other undesirable behaviour. Again, testing should be used to confirm the cause rather than changing the wick blindly.

How to burn test a candle wick

Make test candles using the final wax, fragrance, fragrance percentage, vessel and wick. Allow the candles to condition according to your wax supplier's guidance, then test them in a suitable environment.

Record the wick family and size, vessel diameter, wax, fragrance and concentration. During each burn, observe the flame, melt pool, soot or smoke, mushrooming, vessel temperature and scent performance. Consistent records make it much easier to compare tests.

Why one burn is not enough

A candle can change as it burns down. The first burn is not necessarily representative of later burns, so a proper test should look at the candle across multiple burns and stages of its life.

What happens when you change the vessel?

Changing the vessel diameter, shape or material can change heat distribution and therefore wick performance. A wick that works in one jar should not automatically be assumed to work in another.

What happens when you change fragrance?

A new fragrance should be treated as a formulation change. Even if two fragrances have similar scent profiles, their physical composition can be different. Reassess the burn performance and retest where necessary.

Wick testing checklist

Use this checklist whenever you are developing or changing a candle:

• Record the internal vessel diameter.
• Record the exact wax and wax blend.
• Record the fragrance oil and fragrance percentage.
• Record the wick manufacturer, family and size.
• Record the colourant, if used.
• Make multiple test candles where appropriate.
• Observe performance over repeated burns.
• Keep the successful formula as a written production specification.

Common wick-selection mistakes

Choosing a wick based only on candle weight, copying another maker's wick without matching their wax and vessel, and testing only one wick are common mistakes. Another is judging a wick solely on scent throw. A candle must perform safely and consistently as a complete system.

What makes a good candle wick?

The right wick gives controlled, repeatable performance for the specific candle. You are looking for a stable flame, appropriate melt-pool development and sensible heat without excessive soot or smoke. The answer comes from testing, not from a wick size in isolation.

A note for candle makers selling commercially

If you sell candles, your responsibility goes beyond making a candle that smells good. Finished products should be properly tested and carry the product and safety information required for the market in which they are sold.

Always follow the technical and safety documentation supplied with your materials and applicable UK requirements.

Frequently Asked Questions

How do I know what wick size to use?

Start with the wick manufacturer's guidance based on your vessel diameter and wax, then test a small range of suitable wick sizes in the complete candle formulation.

Should I use the same wick for every fragrance?

Not automatically. Different fragrance oils can affect burn behaviour, so a fragrance change may require additional testing.

Why is my candle tunnelling?

Tunnelling can have several causes, including wick selection, candle dimensions and burn conditions. Review the complete formulation and testing process rather than assuming the wick is the only cause.

Why is my candle producing soot?

Soot can have several causes, including wick size, flame conditions, fragrance, drafts and candle design. A controlled burn test can help identify the cause.

Can I use the same wick in different jars?

Not necessarily. Different internal diameters and vessel designs can change heat distribution. Each significant vessel change should be assessed and tested.