Does fire have a weight?

Yes, fire does indeed have a weight. However, it’s relative to its density. As a plasma – essentially hot air – a fire has around one-quarter of the density of normal air, with the average flame weighing around 0.3 kilograms per cubic metre, or 0.3 grams per litre. Because the density of a flame is lower than air, much like a bubble underwater, it rises, which is why flames flow upwards in air.

A standard candle flame can reach temperatures of around 1,300 Kelvin