How long a candle lasts

A candle's burn time depends mostly on how much wax it holds and how much the flame uses each hour. Labels often state an indicative burn time; if yours does not, or you want to know how many days it will last with your use, this calculator estimates it from the wax weight, the burn rate per wick and the number of wicks. It also tells you how long to keep it lit the first time.

How the calculation works

• Total hours: wax weight divided by the hourly burn rate of all the wicks.
• Days of use: total hours divided by the hours lit per day.
• First burn: about one hour per inch (2.5 cm) of diameter, the time it takes for the wax to melt to the edge.

The burn rate per wick is the least certain figure: for a soy or paraffin jar candle it is often around 4-6 g an hour, for a tea light around 3 g, and a pillar candle can reach 7-8 g. To measure it, weigh the candle before and after a burn of a few hours and divide the difference by the hours.

Typical burn time by type of candle

More wicks do not make a candle last longer: the wax melts faster. A 600 g three-wick candle can burn for less time than a 400 g single-wick one.

The first burn

On the first burn the wax should melt all the way to the edge of the jar. If you put it out earlier, the candle tends to tunnel down the middle and waste wax on the sides. For wide diameters a multi-wick candle is better, so you stay within 4 hours.

The reading bands

• Under 20 hours: a short burn time, typical of tea lights and small candles.
• 20 to 60 hours: a medium burn time, typical of small to medium jar candles.
• 60 hours or more: a long burn time, typical of large or multi-wick candles.

Tips and limits of the calculation

The result is an estimate: drafts, an overly long wick and the type of wax all change the burn rate. Trim the wick to about 5 mm (1/4 inch) before each burn, do not burn for more than 4 hours at a time, and stop using the candle when about 1 cm (1/2 inch) of wax is left at the bottom: in practice the usable hours are a little lower than those calculated. Never leave a burning candle unattended.

Frequently asked questions

How long does an 8 oz (226 g) jar candle last?

At a burn rate of about 5 g an hour with one wick, about 45 hours: at 2 hours a day, just over three weeks.

How long does a tea light last?

A tea light of about 12 g usually lasts 4 hours; long-burning versions last 6-8 hours.

How do I measure my candle's burn rate?

Weigh it, burn it for a few hours, weigh it again and divide the grams lost by the hours.

Do more wicks make a candle last longer?

No: each wick uses wax, so for the same weight the burn time goes down.

How long should I burn a candle the first time?

About one hour per inch of diameter, until the wax melts to the edge, without going past 4 hours.

Why is my candle tunneling?

Usually because the first burns were too short and the wax never reached the edge.

When should I stop using a candle?

When about 1/2 inch (1 cm) of wax is left at the bottom: the container can overheat.

Does it work for every wax?

Yes, if you enter the right burn rate: soy, paraffin and beeswax burn at different speeds.