How much wax and fragrance oil does a candle need?

Start with the water your jar holds

The most reliable way to size a candle container is to fill it with water up to where the wax will stop, and weigh the water. Wax is lighter than water, so multiply by about 0.86 for soy, paraffin and most container blends, or about 0.95 for beeswax. That gives the total weight of wax and fragrance oil the jar holds.

Open the Candle Wax and Fragrance Calculator to do this for one candle or a whole batch.

An 8 oz jar, worked through

Jars are sold by their brim-full capacity in fluid ounces, but you won't fill them to the brim. At 85% full, which leaves about half an inch of space in a small jar:

• Water to the wax line: 8 × 0.85 = 6.8 fl oz, or 201 g.
• Total fill of soy wax and oil: 201 × 0.86 = 173 g (6.1 oz).
• At an 8% fragrance load: 160 g (5.6 oz) of wax and 13 g (0.45 oz) of fragrance oil.

So an "8 oz candle" holds a little over 6 ounces by weight. Fluid ounces measure volume and ounces of wax measure weight, which is where most first batches go wrong. The same jar holds about 191 g (6.7 oz) of beeswax.

Why the oil comes out of the total

Fragrance oil takes up room in the jar too. If you weighed out a full 173 g of wax and then added 8% oil on top, the candle would overflow its wax line. The calculator shares the total between the two:

• wax = total ÷ (1 + load)
• oil = wax × load

For the jar above, 173 ÷ 1.08 = 160 g of wax, and 160 × 0.08 = 12.8 g of oil.

Choosing a fragrance load

Fragrance load is the oil as a percentage of the wax, by weight. Most container waxes are rated for 6–12%, and 8–10% is a common place to start. More oil doesn't always mean a stronger throw: past the wax's limit, oil can seep out and pool on the surface, and the candle may burn poorly. Check your wax maker's maximum.

A few suppliers state the load as a percentage of the total, oil plus wax. Set Load measured as to match your supplier; the total fill stays the same either way.

A batch of candles

For 12 of the 8 oz jars above, add 5% for what stays in the pouring pitcher:

• Wax: 160 g × 12 × 1.05 = 2,018 g (4.45 lb)
• Fragrance oil: 12.8 g × 12 × 1.05 = 161 g (5.7 oz)

A 10 lb bag of wax covers two of those batches, with some left over.

Three ways to size a container

1. Water weight, the most accurate. Tare the empty jar on a kitchen scale, fill it with water to your wax line and weigh it. A jar that holds 210 g of water holds 167 g of soy wax and 13 g of oil at 8%.
2. Measurements, for tins and straight-sided jars. Measure the inside diameter and the height of the wax. A tin 3 inches across filled 2 1/2 inches deep holds 290 ml of water: 231 g (8.1 oz) of wax and 18 g of oil.
3. Capacity, from the listing, with a fill level. Quickest, but less exact, because jars vary and brim capacity includes space you won't fill.

Work out a batch, step by step

1. Under Container, choose Capacity, Measurements or Water weight, and fill in the boxes.
2. Pick your Wax, and set the Fragrance load.
3. Enter the Number of candles and the Extra wax for the pitcher.
4. Weigh out the wax and fragrance oil shown. Weigh the oil too; don't measure it in a spoon.

Add the oil at the temperature your wax's maker recommends, often around 185 °F (85 °C) for soy, and stir gently for two minutes so it binds with the wax.