How to Choose Candle Jars and Containers

Why the container matters so much

In a container candle the flame sits in a small space, and a pool of hot wax presses against the walls. The container has to carry that heat for the whole life of the candle. It also decides how wide your wick needs to be and how much wax fits in.

The National Candle Association says candle glass is made to handle the temperature swings of burning a candle, and that everyday glassware is not. Its advice is to use containers made for candles instead of repurposing ordinary glassware.

The U.S. Consumer Product Safety Commission has recalled glass-jar candles that broke when lit. In one 2023 recall of about 1.21 million three-wick candles, the agency said the wicks burned too close to the side of the glass and caused it to break; there were 12 reports, including one minor cut and one fire. In another 2023 recall of about 5,800 candles, five reports described glass breaking while the candle burned. These were large retail brands, but the lesson applies to every maker: wick, wax, jar and test results come as a set.

Glass, tin, ceramic and concrete compared

Suppliers do not all agree on repurposed jars. One supplier says canning jars made for pressure canning and rated to withstand up to 250°F can be used. The NCA says to use containers made for candles. When in doubt, buy from a candle supplier who says the jar is meant for candles, and test it.

Avoid thin decorative glass (wine glasses, vases, drinking glasses), recycled glass, jars with bubbles or weak seams, plastic, and raw wood, terracotta or clay without sealing. Supplier guidance also warns against using porous materials unsealed because oil and wax can soak in.

Shape, size and wick

• Straight or slightly tapered sides are easiest to wick. A jar that narrows at the top or widens toward the base makes the pool uneven: a wick sized for the top can leave wax unmelted at the bottom.
• A flat, stable base with no pedestal keeps the candle steady.
• Inside diameter at the wax line is the number your wick chart uses. Measure it yourself rather than trusting the listing.
• Wide jars need more than one wick. A supplier says that once a jar goes past roughly 3 to 4 inches across, more than one wick may be needed. Wick charts from several suppliers add multi-wick advice by width. See how to choose a candle wick.

Capacity, fill line and wax weight

A jar’s name is not its wax weight. Many jars were first made for food, and one supplier points out that a jar can be named for how much honey it holds. Suppliers separate three things: the volume to the brim, the amount of wax to your fill line, and the product name. Read the exact listing.

To measure your own: mark the fill line you want, weigh the empty dry jar, fill it with water to the line and weigh again. Multiply by a factor for your wax and confirm with a test pour. How much wax do I need walks through it. The Fill Weight Calculator does the math once you have the water weights.

Leave room between the wax and the rim. Many makers keep a gap so there is space for the flame and the lid. Write the fill line down so every jar matches.

Test the complete candle

An empty jar cannot tell you how the finished candle burns. Wax, fragrance, dye, wick and jar all interact. Supplier guidance says to burn a test candle for at least four hours in a controlled place before committing to a lot of jars, and to repeat across the candle’s life. See the burn test guide.

Watch the flame, soot, melt pool and how hot the jar gets. A flame that burns too close to the glass, or a jar that is too hot to touch, is a reason to put the candle out and change something. Changing the jar means repeating the test, even with the same fragrance.

A short buying checklist

• The supplier sells it for candle use and lists its dimensions.
• The base sits flat, and you can center the wick.
• Walls are straight or lightly tapered, with no bubbles or weak seams.
• You can buy the same jar again and name its exact size or SKU.
• You have budgeted enough jars for test burns, not only for sale stock.
• If it has a lid, it fits, and you know whether it is part of your label plan.

If this is your first container, use one jar size while you learn. Compare candle wax types, and change only one thing at a time.