How 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 mould: 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.

1 Step 1: Your mould

Number of identical cavities you are filling in this batch
Volume of one cavity, measured with water if the mould is unmarked

2 Step 2: Fragrance and margin

Fragrance oil as a percentage of the finished melt weight
Extra wax for shrinkage and wax left in the pot

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 finished melt (wax + oil): fragrance_total = wax_total × (load ÷ (100 − load)). At a 10% load that is wax_total × 10 ÷ 90. 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 moulds need averaging. The 0.86 g/ml density suits soy; paraffin and blends differ slightly (see the wax weight page). Always weigh, never scoop.

How the wax melt calculation works

Unlike container candles, wax melts are sized by mould volume, not vessel dimensions. The calculator multiplies the number of cavities by the volume of one cavity to get the total fill volume, converts that to wax weight with the density 0.86 g/ml, and adds the waste margin — 10% covers shrinkage and the wax film left in the pouring pot.

Fragrance oil is then calculated from the load percentage, which is defined on the finished melt weight: fragrance = wax × (load ÷ (100 − load)). At the 10% default, that is wax × 10 ÷ 90 — so 68.1 g of wax needs 7.6 g of oil, not 6.8 g. The calculator uses the default 10% load because melts carry more fragrance than wicked candles; 8% and 12% are also offered where your wax allows.

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: 61.9 g × 10% = 6.2 g of fragrance oil, dosed on the un-margined wax weight.

The finished batch weighs 74.3 g — about 12.4 g per melt. 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 mould and load.

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 moulds — measure each mould type separately and add the results, rather than averaging.

Fragrance load is the hard ceiling here, not a suggestion. A 12% load is only valid if your wax is rated for it; exceeding the rating causes oil to sweat out of the melts or pool on the surface. Soy waxes typically cap at 10–12%, so check the supplier's maximum.

Finally, cavity volume means filled volume. Decorative moulds 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.

Related calculators

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. 10–12% is standard 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, which is roughly 68 g of wax with margin and 7.6 g of fragrance oil at a 10% load. Larger 3 oz clamshells with 8 segments run about 96 ml, or roughly 91 g of wax plus 10.1 g of oil.

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 moulds where overfilling ruins the shape — enter 90% of the measured volume, or the numbers will overshoot and you will melt too much.

What does a 12% load mean in practice?

It means 12% of the finished melt weight is fragrance oil. On 100 g of wax that works out to 100 × 12 ÷ 88 = 13.6 g of oil, not 12 g — because the percentage is of wax plus oil. Some waxes cannot hold 12%; if yours maxes out at 10%, drop to 10% 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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