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Decibel chart › Loudest sound ever
What is the loudest sound ever recorded?
The loudest sound in recorded history is the 1883 eruption of Krakatoa in Indonesia. Its explosions were heard on Rodrigues, an island about 4,800 km away, and its pressure wave was recorded passing weather stations up to seven times as it circled the Earth. No reliable decibel figure exists, because the nearest gauge was driven off its chart.
Last updated:
Krakatoa, 27 August 1883
The Royal Society’s report on the eruption, published in 1888, collected accounts from around the Indian Ocean. The most remote came from Rodrigues, “very nearly 3,000 English miles from Krakatoa”, where the chief of police wrote that reports were heard during the night “like the distant roars of heavy guns”. The US Geological Survey calls it “the loudest and farthest traveled sound in recorded history”, and the Smithsonian gives the same distance of 4,800 km.
The eruption also sent a pressure wave through the atmosphere that barometers around the world picked up. At many stations it was recorded “not fewer than seven times”: four passages outward from Krakatoa and three more coming back from the opposite side of the planet.
How many decibels was Krakatoa?
Nobody knows. The closest instrument was a pressure gauge at the Batavia gasworks, about 150 km away, and the Royal Society report notes that its trace “passes beyond the limits of the diagram”, so the peak was never recorded. The figure of 172 dB that circulates online comes from a 2014 magazine calculation that starts from a gauge reading the report does not contain. We found no agency or peer-reviewed source that gives Krakatoa a decibel level, so we do not print one.
How loud can a sound get?
In air at sea level, about 194 dB. That is the level of a wave whose pressure swing equals the pressure of the atmosphere itself, and NASA lists 194 dB as the “highest noise level”. Air pressure cannot drop below zero, so this is the ceiling for an ordinary sound wave in air. For a sense of scale, the loudest row on our decibel chart reaches 165 dB, and from 140 dB up there is no safe exposure time at all.
The loudest sounds measured in air
| Sound | Level | What was measured | Source |
|---|---|---|---|
| Saturn V first stage on a NASA test stand | About 204 dB | Sound power, the engine’s total acoustic output (dB re 1 picowatt), not the level at a place | NASA Stennis; Gee et al. 2022 |
| NASA’s Space Launch System at liftoff, Artemis I (2022) | About 162 to more than 170 dB | Sound pressure at sensors two to four nozzle widths from the rocket’s centreline; NASA had expected about 176 dB | Kellison et al. 2025; NASA Kennedy |
| The same launch, from a distance | 127 to 136 dB | Highest sound pressure 1.5 to 5.2 km from the pad | Gee et al. 2023 |
| NASA Glenn’s reverberant acoustic test chamber | 163 dB | Overall sound pressure in the empty chamber, used to test spacecraft with sound | NASA Glenn; NASA/TM-2011-217000 |
The 2022 eruption of Hunga Tonga–Hunga Haʻapai is the closest modern rival to Krakatoa. Its sound was heard about 10,000 km away, including as booms in Alaska, and its pressure wave was tracked around the Earth four times plus three passages from the opposite side; measured that way, the explosion was comparable in size to Krakatoa’s.
Underwater sounds are louder on paper
Underwater decibels are measured against 1 micropascal instead of the 20 micropascals used in air, and water carries sound differently, so for the same intensity an underwater reading comes out 61.5 dB higher: 26 dB from the reference and 35.5 dB from water’s density and sound speed. As NOAA puts it, a decibel underwater “is not equivalent to a dB (re 20 µPa) measured in air”.
| Sound | Level | Notes | Source |
|---|---|---|---|
| Sperm whale click | Up to 236 dB re 1 µPa | The loudest sound recorded from any animal | Møhl et al. 2003; DOSITS |
| Blue whale call | 188 to 189 dB re 1 µPa at 1 m | Long, low moans under 200 Hz | Cummings and Thompson 1971; Širović et al. 2007 |
| Snapping shrimp | 183 to 189 dB re 1 µPa at 1 m | Peak to peak, from one claw snap | Au and Banks 1998; DOSITS |
What is the loudest sound possible?
In air at sea level, about 194 dB. That is the level of a sound wave whose pressure swing equals the pressure of the atmosphere itself, and NASA lists 194 dB as the highest noise level. Air pressure cannot fall below zero, so this is the ceiling for an ordinary sound wave in air.
How loud is a rocket launch?
Sensors close to NASA’s Space Launch System recorded about 162 to more than 170 dB at the Artemis I launch in 2022, and 127 to 136 dB at 1.5 to 5.2 km away. NIOSH’s exposure rule allows about 2 seconds a day at 127 dB, and nothing at all from 140 dB up.
What is the loudest animal?
The sperm whale, whose clicks reach 236 dB underwater. Underwater decibels use a different reference pressure and water carries sound differently, so the number cannot be set against decibels measured in air.
Everyday sounds are far below any of this. To see where your own surroundings sit, use the free online decibel meter, or look up a single level such as 150 decibels.
Sources: Royal Society, The Eruption of Krakatoa (1888), pp. 63, 69, 79; USGS Volcano Watch; Smithsonian, Forces of Change; NOAA NCEI; University of Illinois, PHYS 406 notes; NASA Kennedy, 2002; NASA Stennis; Gee et al. 2022; Kellison et al. 2025; NASA Kennedy, 2019; Gee et al. 2023; NASA Glenn; NASA/TM-2011-217000; Matoza et al. 2022; DOSITS, University of Rhode Island; NOAA Technical Memorandum NMFS-NWFSC-89; Møhl et al. 2003; Cummings and Thompson 1971; Širović et al. 2007; Au and Banks 1998.
