Candle Wick Size Guide
Enter your jar diameter and wax type to get primary and secondary wick recommendations across all four major wick series - side by side. Adjusts for fragrance load automatically. Nothing uploaded.
Jar Settings
Wick Recommendations
| Series | Primary ? | Secondary ? | Diameter range |
|---|
Test protocol
- Burn for 1 hour per inch of jar diameter (minimum 2 hours).
- Melt pool should reach the jar edges within that time.
- Flame should be steady, 1-3cm tall, no black smoke.
- Mushrooming (carbon ball on wick tip) = wick too large - try primary next time.
- Tunnelling (melt pool doesn't reach edges) = wick too small - step up to secondary.
Wick Test Log
Learn more: wick sizing and candle testing
Why wick selection matters most
The fragrance, colour, and wax are all visible. The wick is invisible - until it goes wrong. A wick one size too small causes tunnelling, where the candle burns straight down the centre leaving thick unused wax around the edges. A wick too large mushrooms (builds up a carbon ball at the tip), produces black smoke, and creates a dangerously large flame. Finding the right wick for your specific jar diameter and wax combination is the single most important step in candle development.
Wick series: CD vs ECO and beyond
Both CD and ECO are coreless cotton wicks from the same manufacturer (Wedo). CD wicks have a slightly stiffer braid and are often preferred for soy wax. ECO wicks have a paper filament added during braiding which helps keep the wick upright and promotes a cleaner burn. ECO wicks tend to produce a bit more flame and are popular for paraffin-soy blends. Cotton Core and Wood Wick series offer alternative burn profiles. In practice, testing multiple sizes within your chosen series is recommended as results vary by fragrance.
How fragrance load affects wick size
Higher fragrance oil concentrations make the wax more viscous and slow the burn rate, causing the melt pool to not reach jar edges. For fragrance loads above 8-10%, stepping up one wick size is common practice. Very heavy loads (10%+) may require stepping up two sizes. This guide automatically adjusts recommendations based on your chosen fragrance load.
Test protocol and melt pool rules
Burn for 1 hour per inch of jar diameter (minimum 2 hours). The melt pool should reach the jar edges within that time. Flame should be steady, 1-3cm tall, with no black smoke. Mushrooming means the wick is too large - try the primary size next time. Tunnelling means the wick is too small - step up to the secondary size.
FAQ
What wick do I need for a 75mm soy jar?
For a 75mm inner diameter jar with soy 464 at standard fragrance load, CD-12 or ECO-6 is a good starting point. Always test for at least 2-3 hours - the melt pool should reach the jar edges within that window.
Why is paraffin shown as needing a smaller wick than soy?
Paraffin wax has a lower melting point and higher thermal conductivity than soy, so it burns at a higher temperature and spreads heat more easily. A wick sized for soy would produce an oversized flame in paraffin. The guide steps down one size for paraffin as a starting baseline.
Do I need to test every wick series?
No. Most candle makers pick one wick series and test within it. CD and ECO are the most widely available. Wood wicks require a different test protocol and burn differently. Test the primary size in your chosen series first, then adjust from there.