The eruption is estimated to have had a Volcanic Explosivity Index of 7. It had 4–10 times the energy of the 1883 Krakatoa eruption. An estimated of pyroclastic trachyandesite was ejected, weighing approximately 1.4×1014 kg. This has left a caldera measuring across and deep. The density of fallen ash in Makassar was 636 kg/m3. Before the explosion, Mount Tambora was approximately high, one of the tallest peaks in the Indonesian archipelago. After the eruption of 1815, the maximum elevation has been reduced to .