Candle Wax Calculator: How Much Wax and Fragrance Oil per Jar

Three ways to size a jar, and which to trust

Every candle wax calculator needs the same thing first: how much candle fits in the jar. There are three ways to get it, and they are not equally good.

Weighing water is the most accurate. Put the empty jar on the scale, press tare, and fill it with water to where the top of the wax will sit, usually about half an inch below the rim. The number on the scale is the weight of water that fits. Wax is lighter than water, so multiply by 0.86 and you have the weight of finished candle that fits in the same space. This works for any shape, including tapered tumblers, square jars and odd vintage glass that no formula can handle.

The fl oz on the listing is a good second. Supply shops sell jars by fluid ounces. The catch is that some list the volume to the brim and some to a typical fill line. The calculator converts fl oz to milliliters (one US fl oz is 29.57 ml), takes the fill level you choose, and applies the same 0.86 factor. If you try a new jar style, weigh water once and compare. It takes two minutes and saves a batch.

Measuring the jar works for straight sides. For a round jar with straight walls, the inside diameter and the height of the wax give the volume of a cylinder. It falls apart for tapered tumblers, bowls and anything with a thick base, which is why the calculator tells you to weigh water for those.

What the 0.86 actually means

A cup of melted soy wax weighs less than a cup of water. Soy and paraffin container waxes settle at roughly 0.86 times the weight of water once they set, and that number is what most supply shops build into their own calculators. It is an average, not a law. A wax heavy in additives can be denser, and a candle poured very hot shrinks a little more as it cools.

If you find your candles keep coming up a little short of the fill line, nudge the factor up to 0.88. If you are left with a puddle in the pitcher every time, drop it to 0.84. Note the number that works for your wax and jar and keep using it.

Common jar sizes at a glance

Here is what the calculator gives for common jar sizes at a 90% fill, the 0.86 factor and an 8% fragrance load of the wax. Use it to sanity check your order before you buy wax. Your own jars will differ a little.

Jar (fl oz, brim)	Finished candle	Wax	Fragrance oil
4 fl oz	3.23 oz	2.99 oz	0.24 oz
6 fl oz	4.84 oz	4.49 oz	0.36 oz
8 fl oz	6.46 oz	5.98 oz	0.48 oz
9 fl oz	7.27 oz	6.73 oz	0.54 oz
10 fl oz	8.07 oz	7.48 oz	0.60 oz
12 fl oz	9.69 oz	8.97 oz	0.72 oz
16 fl oz	12.92 oz	11.96 oz	0.96 oz

Notice that the finished candle in an “8 oz” jar weighs about 6.4 oz, not 8. That gap trips up a lot of new makers, both when buying wax and when writing the net weight on the label. The net weight line belongs to what is actually in the jar, which is why the result above includes it. For the full rules on that line, see the label net weight calculator.

Fragrance load: two meanings of the same number

When a supplier says a wax holds 10% fragrance, almost every US shop means 10% of the wax weight: for one pound of wax (16 oz), you add 1.6 oz of oil. Candles Molds, Lone Star and CandleScience all write it this way. Some calculators, including Craftybase, treat the percent as a share of the whole candle instead. The oil amounts are close but not the same: 10% of the finished candle is 11.1% of the wax.

Neither is wrong, but mixing them up is how people end up over their wax’s limit without knowing it. This calculator lets you pick either, shows the result in both forms, and if you choose your wax, it checks the load against every published maximum we have for it. When suppliers disagree, it tells you so instead of picking one. You can see the full comparison on the wax specs page.

Before a big batch

Pour one candle with the numbers above, let it cure, and burn it. If the scent is weak, more oil is rarely the fix; a different wick size or a longer cure usually helps more. The wick test planner sets up that test.

From one candle to a batch

Set “How many candles” and the wax and oil scale up together. For a pour day with different jars, tins and wax melts all at once, the pour day planner is easier: it adds a little extra for what sticks to the pitcher and splits the batch into loads that fit your melting pot.

Read our guides

Why your 8 oz jar holds about 6.4 oz of candleFluid ounces measure space and ounces measure weight. Here is how the two meet in a candle jar, and the one-minute water test that settles it.A US candle label checklist, line by lineWhat goes on a candle label sold in the US: product identity, net weight in ounces and grams, maker’s name and address, type size, placement and safety warnings.

Questions makers ask

How much wax do I need for an 8 oz candle?

An “8 oz” jar is usually 8 fl oz to the brim. Filled to about 90% with soy wax, the candle weighs about 6.4 oz, which at an 8% fragrance load is about 5.9 oz of wax and 0.5 oz of oil. Weigh water in your own jar for an exact number, because jars sold as 8 oz vary.

Why multiply water weight by 0.86?

Melted and set wax is lighter than water for the same space. Soy and paraffin candle wax land around 0.86 times the weight of water, which is the number most supply shops use. Your wax may be 0.84 to 0.90, so if your candles come out short or overfilled, adjust the factor and remember it for next time.

Is fragrance load a percent of the wax or of the whole candle?

Most US suppliers mean percent of wax weight: 10% of 1 lb of wax is 1.6 oz of oil. Some calculators, including Craftybase, mean percent of the finished candle. The difference is small at low loads but real: 10% of the candle equals 11.1% of the wax. Pick the one your supplier uses in the “Percent of” box.

Can I use fl oz on the jar label instead of weighing water?

Yes, as a starting point. The calculator converts fl oz to milliliters, takes your fill level, and multiplies by the wax factor. Jar listings sometimes give the size to the brim and sometimes to the usual fill line, so weigh water once when you get a new jar style.

Should I melt extra wax?

Yes, a little. Wax sticks to the pitcher and some goes into a test jar. Many makers add 5 to 10% for a batch. The pour day planner adds this for you and splits the batch into pots.

Does adding dye change the amount of wax?

Not in any way that matters. Dye is a tiny fraction of a percent of the batch. Fragrance oil is the ingredient that takes real weight away from the wax.

Sources we checked

Numbers last checked 2026-10-21. How we check them. If your supplier says something different, tell us.