Candle Wax CalculatorHow Much Wax and Fragrance Oil Do Wax Melts Need?
Wax melts look simple — no wick, no container — but getting the amounts right still matters, especially with the high fragrance loads melts are famous for.
This calculator sizes your batch from your mold: how many cavities, how big each one is, and your fragrance load. It returns the wax to melt and the oil to add, in grams.
Wax melt calculator
Enter how many melt cavities you are filling and the size of each one, and this calculator returns the wax and fragrance oil to melt — with the higher fragrance loads that wax melts are known for.
How the wax melt formula works
Total fill volume is simply cavities × cavity_ml. That volume is multiplied by 0.86 g/ml (the density of soy wax, the most common melt wax) to get the wax weight, then increased by the waste margin: wax_total = cavities × cavity_ml × 0.86 × (1 + margin ÷ 100).
Fragrance oil follows the same convention as container candles — the load is a percentage of the wax weight, dosed before the margin: fragrance_total = un-margined wax × (load ÷ 100). At the 10% default that is the wax weight × 0.10 — 10 g of oil per 100 g of wax. Because melts have no wick and a high fragrance load is their whole selling point, 10% is the default here instead of the 8% used for container candles.
Limits: cavity sizes are assumed identical — mixed molds need averaging. The 0.86 g/ml density suits soy; paraffin and blends differ slightly (see the wax weight page). Always weigh, never scoop.
Limitations of the calculation
The calculation assumes every cavity is the same size. If you are pouring a mixed batch — say clamshells plus a few shaped molds — measure each mold type separately and add the results, rather than averaging.
Fragrance load is the hard ceiling here, not a suggestion. Loads above 10% are only valid if your wax is rated for them; exceeding the rating causes oil to sweat out of the melts or pool on the surface. Soy waxes typically cap at 10%, so check the supplier's maximum.
Finally, cavity volume means filled volume. Decorative molds that you only fill partway, or clamshells filled below the rim, need the actual fill volume entered — otherwise you will melt more wax than you pour.
Worked example: a 6-cavity clamshell
Take a standard clamshell with 6 segments of 12 ml each, poured at a 10% fragrance load with a 10% margin.
Step 1 — total volume: 6 × 12 ml = 72 ml.
Step 2 — wax weight: 72 ml × 0.86 g/ml = 61.9 g, plus 10% margin → 68.1 g of wax to melt.
Step 3 — fragrance oil: 10% of 61.9 g (the wax before the margin) = 6.2 g of fragrance oil.
The finished batch — the un-margined wax plus the oil, what actually ends up in the melts — weighs 61.9 + 6.2 = 68.1 g, about 11.4 g per melt. What you weigh out is the margined wax plus the oil: 68.1 + 6.2 = 74.3 g.
Larger clamshell — 8 segments: 8 × 12 ml = 96 ml; 96 × 0.86 × 1.10 = 90.8 g of wax, and 10% of 82.6 g = 8.3 g of fragrance oil. The finished batch is 82.6 + 8.3 = 90.8 g (about 11.4 g per melt); what you weigh out is 90.8 + 8.3 = 99.1 g.
Weigh both on a scale, melt the wax, add the oil at the right temperature, and pour. The calculator above repeats these steps for any mold and load.
Related calculators
- Fragrance Oil to Wax Ratio CalculatorFree fragrance oil to wax ratio calculator: enter your wax weight and load % to get the fragrance oil in grams, with the formula explained.
- Soy Wax CalculatorFree soy wax calculator: enter container diameter, height, and candle count to get wax and fragrance oil amounts in grams, with a worked example.
- Candle Wax Cost CalculatorCalculate candle batch costs with this free wax cost calculator.
Try the candle wax calculator for every calculator on one page.
Frequently asked questions
Why do wax melts use higher fragrance loads than candles?
Because there is no wick, makers push fragrance harder in melts — and buyers expect it. A 10% load is the standard working load for soy wax melts, compared with 6–8% for container candles. The trade-off is that very high loads can make melts sweaty or crumbly, so stay at or under your wax's rated maximum.
How do I find the volume of one clamshell segment?
Melt one full cavity: pour water into a single segment up to the fill line, then pour that water into a measuring cup or weigh it (1 g = 1 ml). Most standard clamshell segments hold 10–15 ml each. Enter the per-cavity volume above and the calculator multiplies by your cavity count.
How much wax does a standard clamshell need?
A standard 2.5 oz clamshell has 6 segments of about 12 ml — 72 ml total. The worked example above gives the exact wax and fragrance oil for that clamshell, plus the larger 8-segment size.
Do I fill the cavities right to the top?
The cavity volume in the calculator is the fill volume. If you only fill to 90% of a cavity — common with decorative molds where overfilling ruins the shape — enter 90% of the measured volume, or the numbers will overshoot and you will melt too much.
What is the maximum fragrance load for wax melts?
A 12% load means 12 g of oil per 100 g of wax — and it exceeds the conservative 10% ceiling for soy wax, so this calculator does not offer it. Some waxes cannot hold even 10%; if yours maxes out lower, drop to its rating rather than risking sweating.
Can I use paraffin or beeswax for melts?
Yes, but the numbers change. Paraffin holds fragrance well and is common for melts; beeswax is harder to scent and usually stays at lower loads. The calculator's 0.86 g/ml density is for soy — paraffin is about 0.90 and beeswax about 0.96, so paraffin batches weigh a little more for the same volume. Use the wax weight page for other waxes.
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