Wax Melt Tart Calculator
Calculate wax, fragrance oil, and dye amounts for making wax melt tarts and clamshell molds.
Wax melts (also called wax tarts) are wickless scented wax pieces designed to be melted in an electric warmer. Because there is no flame and no wick, wax melts can handle higher fragrance loads than candles — making them intensely aromatic.
Wax Volume Calculation
Total wax needed = Number of molds x Cavity volume x Wax density
Most wax melt molds are measured by weight capacity, not volume. Standard clamshell molds hold 2.5 oz (71g) total across 6 cavities, so each cavity holds approximately 0.42 oz (12g).
Standard Mold Sizes
| Mold Type | Total Capacity | Cavities | Per Cavity |
|---|---|---|---|
| 6-cavity clamshell | 2.5 oz (71g) | 6 | 0.42 oz (12g) |
| 6-cavity clamshell (large) | 3.5 oz (99g) | 6 | 0.58 oz (16.5g) |
| 10-cavity clamshell | 4.0 oz (113g) | 10 | 0.40 oz (11.3g) |
| Silicone heart/star mold | Varies | 6–12 | 0.3–0.5 oz each |
| Wax brittle (snap bar) | 2.8 oz (79g) | 1 (scored into pieces) | N/A |
Fragrance Load
Wax melts perform best at 8–12% fragrance load. Since there is no flame, there is no risk of the fragrance causing a fire hazard (unlike candles where 6–8% is the safe maximum).
Fragrance oil weight = Total wax weight x (Fragrance percentage / 100)
Worked Example — 10 Standard Clamshells
Mold capacity: 2.5 oz (71g) each. Number of clamshells: 10. Total wax needed: 10 x 71g = 710g of wax. Fragrance load (10%): 710 x 0.10 = 71g of fragrance oil. Total pour weight: 710 + 71 = 781g.
But wait — you need to account for the wax that sticks to the melting pot and tools. Add 10% waste: Total wax to melt: 710 x 1.10 = 781g. Total fragrance: 71g (no waste added — fragrance goes directly into the pour pot).
Wax Type Comparison for Melts
| Wax | Fragrance Throw | Max FO Load | Melt Pool Temp | Cost |
|---|---|---|---|---|
| Soy (464) | Good | 10% | 46–57°C (115–135°F) | Low |
| Paraffin (IGI 4630) | Excellent | 12% | 54–65°C (130–150°F) | Low |
| Parasoy blend | Very good | 11% | 49–60°C (120–140°F) | Medium |
| Coconut wax | Very good | 10% | 40–52°C (104–125°F) | High |
| Beeswax | Moderate | 6% | 62–65°C (144–149°F) | Very high |
Paraffin gives the strongest hot throw (scent while melting) but soy is preferred by customers who want a “natural” option.
Dye Usage
Liquid dye: 2–4 drops per 100g of wax for pastels, 6–10 drops for vivid colors. Dye blocks: 1/4 block per 450g (1 lb) for light color, 1/2 block for medium. Mica powder: 0.5–1g per 100g of wax. Mica does not fully dissolve and creates a shimmer effect.
Pouring Temperature
Pour wax melts at a lower temperature than candles for better tops:
- Soy wax: 60–66°C (140–150°F)
- Paraffin: 71–77°C (160–170°F)
- Parasoy: 65–71°C (149–160°F)
Add fragrance oil 5°C above the pouring temperature and stir for 2 full minutes to ensure complete binding.