Wax Melt Tart Calculator

Wax melts (also called wax tarts) are wickless scented wax pieces designed to be melted in an electric warmer.
With no flame and no wick to clog, they carry more fragrance than a candle can, which is why a single cube can scent a room.

The mistake that overflows every mold

A clamshell is sold by what it HOLDS, not by how much wax goes into it. A 2.5 oz (71 g) clamshell holds 71 g of finished melt, and the fragrance oil is part of that 71 g. It does not sit on top of it.

So the fragrance comes OUT of the mold capacity:

Wax = Mold capacity ÷ (1 + fragrance % / 100) Fragrance oil = Mold capacity − Wax

Get that backwards and at a 10% load you mix 71 g of wax with 7.1 g of oil, then try to pour 78 g into a 71 g mold. It runs over the divider between cavities, and you lose the batch to a single sheet of scented wax.

Most wax melt molds are measured by weight capacity, not volume. Standard clamshell molds hold 2.5 oz (71 g) total across 6 cavities, so each cavity holds about 0.42 oz (12 g) of finished melt.

Standard Mold Sizes

Fragrance Load

Wax melts sit comfortably at 8 to 12%. The ceiling is set by how much oil the wax can actually hold rather than by fire safety, since there is no flame here. Container candles run to a similar maximum, around 10 to 12% for soy, paraffin and coconut and closer to 6 to 8% for beeswax, but most makers land at 6 to 8% because that is where soy throws best.

Push past the wax’s limit and the oil does not evaporate into the room. It sweats out and leaves a greasy film on the clamshell.

Worked Example, 10 Standard Clamshells at 10%

Mold capacity: 2.5 oz (71 g) each, so 10 clamshells hold 710 g of finished melt.

Wax: 710 ÷ 1.10 = 645 g Fragrance oil: 710 − 645 = 65 g Poured weight: 645 + 65 = 710 g, which is exactly what the molds hold.

Then allow for the wax that stays behind on the pot, the pouring pitcher and the thermometer. Ten percent extra on the wax alone:

Wax to melt: 645 × 1.10 = 710 g

Fragrance gets no waste allowance, because it goes straight from the bottle into the pour pot and nothing clings to the glass worth counting.

Wax Type Comparison for Melts

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)
• Coconut wax: 57–63°C (135–145°F)

Add fragrance oil 5°C above the pouring temperature and stir for 2 full minutes to ensure complete binding.