Candle Burn Time Calculator

In short Burn time is weight divided by burn rate and nothing more, which makes the rate the only interesting part. A 243 gram candle burning at 7 grams an hour lasts about 34 hours and 43 minutes. Run it the other way — 34.71 hours at 7 grams an hour — and you get the 243 grams back, which is the check that the arithmetic is honest in both directions. THE THING PEOPLE GET WRONG IS THAT A WIDER CANDLE DOES NOT LAST PROPORTIONALLY LONGER. Burn rate follows the MELT POOL DIAMETER, not the amount of wax underneath it. Make a candle bigger by using a wider jar and the rate goes up with it, so the burn time rises far less than the weight does and the burn time PER GRAM actually falls. Make it bigger by using a taller jar of the same diameter and the time really does roughly double. That is why hours per gram only compares candles of the same width, and why a big three-wick can burn through its wax faster than a small single-wick. THERE ARE TWO WAYS TO GET A RATE AND ONLY ONE OF THEM IS YOURS. This page will take a typical figure for a given melt-pool diameter, which is a convention and moves with the wick, the wax, the fragrance load and even the draught in the room. Or you can measure: weigh the candle, burn it for a timed session, weigh it again, and the difference over the hours is your rate. That takes about as long as an evening and beats every chart, provided you measure on a full-width melt pool rather than the first burn, which runs slower before the pool reaches the glass. TWO CAVEATS ON THE NUMBER ITSELF. It is total burn hours, not evenings: the usual advice is to burn until the melt pool reaches the edge, often two to four hours, and stop, so a 35 hour candle is roughly a dozen sessions. And the last few grams do not count — a container candle is normally retired with ten millimetres or so of wax left, for the sake of the glass and the wick tab, so the usable time is slightly under the figure. Nothing here models the flame, the glass temperature, or when it stops being safe to keep burning.