The arithmetic
Divide the price by the burn time. The two candles below are invented to show the arithmetic — they are not real products, and these are not prices we observed anywhere. A hypothetical $30 candle rated for 60 hours works out at $0.50 an hour. A hypothetical $15 candle rated for 30 hours works out at $0.50 an hour too, despite costing half as much on the shelf.
That is the point of the measure. Shelf price and cost of use are different numbers, and only the second describes what you get for the money. To run it on a real candle, use the calculator with a price and a burn time you have checked yourself.
What this guide does not compare
This guide does not compare these materials' performance, cost, prevalence, blend composition, cosmetic behavior, or health effects. We have not collected attributable evidence for any of those comparisons, and we will not publish one without it.
Weight, wick count, vessel and wax are all things a label may state. We take no position on what any of them does to a burn time, because we have not measured it and have found no measurement we could attribute to anyone.
What we publish instead
On Ember & Main, each burn figure identifies its publisher and we preserve documented disagreements. That is the whole of what we assert about burn time: who stated which figure, on which page, on which date.
Where two publishers give different figures for the same candle, both are recorded and the gap is shown rather than resolved into a single number we would have had to choose.
How to use it when you shop
Work out cost per hour before you compare anything else. It collapses price, size and burn time into one figure, and a discount moves it directly because the price is the numerator.
Then apply judgement the number cannot capture. Throw, vessel quality, and whether you enjoy the scent are worth real money. The point is not to buy the cheapest hour available. It is to know what an hour costs before you decide.