Amp Wattage vs Loudness Calculator

Wattage is not loudness, decibels are logarithmic, and the speaker matters as much as the amp. This tool does the real math instead of the "double the watts, double the volume" myth, so you can actually see how much louder one rig is than another.

Amp A

Wattage Speaker sensitivity (dB, optional)

Amp B

Wattage Speaker sensitivity (dB, optional)

Output difference +8.2 dB

Perceived loudness Amp B sounds about 1.8× as loud

Raw power ratio 6.7× the watts

Notice the gap between the raw power ratio and the perceived loudness. That gap is the entire point: watts scale linearly, your ears don't.

Speaker sensitivity (measured in dB at 1 watt / 1 meter, printed on most speaker spec sheets) matters as much as amp wattage, because a 6 dB difference between two speakers is a doubling of sound pressure and roughly 1.5 times as loud to the ear (using the same 10 dB-per-doubling rule this calculator uses), independent of the amp behind it. Leave both sensitivity fields equal if you're only comparing amp heads through the same cab. This is a simplified estimate of maximum output potential, not a prediction of how loud you'll actually play something, since the volume knob and your right hand still decide that. For the full breakdown of every real way to manage a too-loud tube amp, read the ranked fixes.

Watts to decibels: the math

Watts measure power. Decibels compare two levels on a logarithmic scale. The difference in decibels between two amps on the same speaker is 10 × log10(watts B ÷ watts A). Doubling the watts always adds about 3 dB, whether you go from 15 to 30 or from 100 to 200. A rule of thumb used by this calculator is that it takes about 10 dB for something to sound twice as loud, so a 3 dB gain is about 1.23 times as loud. It is a noticeable but modest change.

Power change	Difference	Sounds about
2× the watts	+3.0 dB	1.23×
4× the watts	+6.0 dB	1.52×
10× the watts	+10.0 dB	2.00×
100× the watts	+20.0 dB	4.00×

Common amp comparisons

Assuming the same speaker sensitivity, here is how typical wattage jumps compare.

Compare	Watts ratio	Difference	Sounds about
15 W to 30 W	2.0×	+3.0 dB	1.23×
30 W to 50 W	1.7×	+2.2 dB	1.17×
15 W to 50 W	3.3×	+5.2 dB	1.44×
50 W to 100 W	2.0×	+3.0 dB	1.23×
30 W to 100 W	3.3×	+5.2 dB	1.44×
15 W to 100 W	6.7×	+8.2 dB	1.77×
100 W to 200 W	2.0×	+3.0 dB	1.23×
100 W to 240 W	2.4×	+3.8 dB	1.30×
100 W to 500 W	5.0×	+7.0 dB	1.62×

How many decibels is a 240 watt amp?

An amp's wattage does not convert to one decibel figure on its own. Loudness depends on the speaker, and speaker sensitivity (dB at 1 watt, 1 meter) sets the starting point. In an idealized case, the maximum level at 1 meter is the speaker sensitivity plus 10 × log10(watts). So a 240 watt amp into a 98 dB speaker peaks at about 121.8 dB at 1 meter. Real playing levels are lower: the volume knob, power compression, your room and your distance all change the result, so treat these as ceilings, not predictions.

Amp power	95 dB speaker	98 dB speaker	101 dB speaker
1 W	95.0 dB	98.0 dB	101.0 dB
5 W	102.0 dB	105.0 dB	108.0 dB
15 W	106.8 dB	109.8 dB	112.8 dB
30 W	109.8 dB	112.8 dB	115.8 dB
50 W	112.0 dB	115.0 dB	118.0 dB
100 W	115.0 dB	118.0 dB	121.0 dB
240 W	118.8 dB	121.8 dB	124.8 dB

Hearing safety matters at these levels. NIOSH recommends limiting exposure to an average of 85 dBA over eight hours and cutting the allowed time in half for every 3 dB increase. At 100 dB, that limit is about 15 minutes. If a tube amp is simply too loud for where you play, read the ranked fixes.

Frequently asked questions

Is 100 watts twice as loud as 50 watts?

No. Doubling the wattage adds about 3 dB, which sounds roughly 1.23 times as loud using the usual rule that 10 dB sounds twice as loud. You would need about ten times the power for a doubling.

How many decibels is a 240 watt amp?

It depends on the speaker. In an idealized case the peak level at 1 meter is the speaker's sensitivity plus 10 x log10(watts). With a 98 dB speaker that is about 121.8 dB. Real playing levels are lower than that peak.

How do I convert watts to decibels?

You cannot convert watts to decibels directly, because loudness depends on the speaker. To compare two amps, use 10 x log10(watts B / watts A). For an absolute level at 1 meter, add the speaker sensitivity.

Does speaker sensitivity matter as much as wattage?

Yes. A speaker that is 3 dB more sensitive gives you the same output boost as doubling the amp's power. Our calculator lets you enter the sensitivity of each setup so you can compare the whole rig.

How loud is too loud for your hearing?

NIOSH recommends an average of 85 dBA over eight hours as the exposure limit, with the allowed time halving for every 3 dB increase. At 100 dB that is about 15 minutes.