Generally, smaller candles such as votives with smaller wicks will burn at a rate of 7-9 hours per ounce of wax used. For example, a two ounce votive may be expected to burn for 14-18 hours. Larger candles with larger wicks will consume wax at a faster rate. The larger wicks can be expected to yield 5-7 hours per ounce of wax used. So, a 16 ounce canning jar, which actually holds only about 12 ounces of wax (by weight), could be expected to burn anywhere from 60-84 hours.
There are many variables that will affect the actual burn time of your finished candles; the type of wax used, the additives used, the type of wick used, etc. With so many variables, an actual burn test is often required to get an accurate estimate of the burn time of your candles.
Here is a calculator that will allow you to find a very close estimate of the total burn time of a candle, without actually having to burn it for the entire duration. You’ll still have to burn it for a few hours though, and you will need to record a few measurements.
You’ll need a fairly accurate scale for this. Postal scales work fine.
1. First, measure the initial weight of your unburned candle. If your scale allows it, make all your measurements in grams. Otherwise, measure to the nearest fraction of an ounce. This is your initial weight.
2. Next, burn your candle for 3 or 4 hours. You may wish to repeat the burn cycle several times. Record the total time that you burned your candle. This is your duration of test burn.
3. Now measure the weight of your candle again using the same units that you did above (grams or ounces). This is your final weight.
4. If you are using a container, measure the weight of the empty container. This is your empty container weight.
5. Enter the values and click Calculate