Candle Melt Pool Diameter Calculator
Calculate the expected melt pool diameter for your candle based on wick size, wax type, and container diameter.
The melt pool is the circular area of liquefied wax that forms when a candle burns. A proper melt pool should reach the full diameter of the container within 1–2 hours of burning. If the melt pool is too small, the candle “tunnels” — wasting wax along the walls. If the melt pool is too large or too deep, the candle may overheat, smoke, or become a fire hazard.
Melt Pool Rule
The ideal melt pool reaches edge to edge within the first burn (1–2 hours) and should be 6–13 mm (¼–½ inch) deep. The primary factor controlling melt pool diameter is wick size relative to container diameter.
Wick Heat Output Estimation
Different wick series have known melt pool diameters. A simplified model:
Expected Melt Pool Diameter = Wick Throw Diameter × Wax Factor
Where:
- Wick Throw Diameter is the rated melt pool size for the wick series and size number
- Wax Factor adjusts for wax type: Soy = 0.85, Paraffin = 1.0, Coconut blend = 0.90, Beeswax = 0.80, Palm = 0.95
Wick Series Reference (Approximate Melt Pool Diameters)
| Wick Size | CD Series | ECO Series | HTP Series |
|---|---|---|---|
| Small | 5.0 cm (2 in) | 5.0 cm (2 in) | 5.0 cm (2 in) |
| Medium | 7.5 cm (3 in) | 7.0 cm (2.8 in) | 7.5 cm (3 in) |
| Large | 9.0 cm (3.5 in) | 8.5 cm (3.3 in) | 9.0 cm (3.5 in) |
| X-Large | 11.0 cm (4.3 in) | 10.0 cm (4 in) | 10.5 cm (4.1 in) |
Worked Example
A container with 8 cm diameter, using a medium ECO wick in soy wax:
Expected melt pool = 7.0 × 0.85 = 5.95 cm
This leaves about 1 cm of unmelted wax on each side — the wick is too small. You would need to size up to a large ECO wick: 8.5 × 0.85 = 7.2 cm, which is much closer to the 8 cm container edge.
Multi-Wick Candles
For containers wider than 10 cm (4 inches), a single wick often cannot achieve a full melt pool. Use multiple wicks spaced evenly. Each wick contributes its own melt pool, and where pools overlap they merge. Space wicks 5–7 cm apart for optimal coverage.
Testing Is Essential
This calculator provides a starting point, but every candle must be test-burned. Factors like fragrance oil load (which softens wax), dye concentration, ambient temperature, and container material all affect the actual melt pool. Always perform a minimum 4-hour test burn and measure the actual melt pool diameter.