A big consideration in candlemaking is burn rate – or the amount of wax consumed by the wick in a given time point. The lower the burn rate, the less wax will be burned. So if you buy a candle that promises a 36-hour burn rate that means the candle will burn for about 36 hours with a small wax consumption per hour. Many different factors like wick, wax, fragrance, oil, container and climate may alter the burn rate but before selling candles, it’s important to provide a burn rate. I can’t tell you the number of three-wick candles I’ve bought from Bath & Body Works or Kohl’s only to be disappointed by their 12-hour burn rate while a higher-cost similar-sized candle may burn for three times as long.
So before lighting a candle you’ve just made, weigh it in ounces. Burn it for three hours. Weight it again. First zero out if you’re using some sort of candle container – you only want to weight the WAX and WICK. Minus the first number from the second number and you’ll see the number of ounces burned in three hours. Divide by three to find the ounce burned per hour. Now multiply this number by the number of ounces in the candle – voila, burn time!
Ok so, if you have a 20 ounce candle that weights 19 ounces after burning you’re burning 3 ounces in 3 hours, so 1 ounce per hour. 1 ounce times a 20 ounce candle. This candle has a burn time of 20 hours. Easy!