Sensitivity is how loud a speaker plays for one watt of amplifier power, measured at one metre and quoted in decibels. It appears in the spec table for the 78 passive speakers here that publish it. The scale is logarithmic, so differences that look small are not: every 3 dB of sensitivity halves the amplifier power you need for the same volume.
Most modern passive speakers cluster in the mid 80s. Values in the low 90s are genuinely uncommon, because designers who want deep bass from a compact cabinet have to trade efficiency away to get it.
Why 3 dB Matters So Much
Sensitivity compounds. Each 3 dB step halves or doubles the power required:
- An 87 dB speaker needs twice the power of a 90 dB one for the same loudness.
- It needs four times the power of a 93 dB one.
- An 84 dB speaker needs eight times the power of that 93 dB speaker.
In practice this is the difference between a speaker a low-power amplifier can drive and one it cannot. Reaching a realistic listening level in an ordinary room might ask around 100 watts of an insensitive bookshelf speaker while a high sensitivity design gets there on roughly 10.
This is also why sensitivity, not wattage, is the number to look at first when matching speakers to an amplifier. See speaker watts explained for why the power rating on the box tells you much less than it appears to.
How The Figure Gets Measured, And Why It Is Often Flattering
There are two common measurement conventions and manufacturers do not always say which one they used.
One watt at one metre is the honest version. A signal calibrated to deliver exactly one watt into the speaker’s nominal impedance, measured a metre away.
2.83 volts at one metre is the more common version. 2.83 volts delivers one watt into 8 ohms, but into a 4 ohm speaker it delivers two watts. A 4 ohm speaker measured this way reads about 3 dB higher than its true one watt figure, which is a meaningful advantage on a spec sheet and no advantage at all in your room.
Because of this, sensitivity is only strictly comparable between speakers of the same impedance, and a published figure should be treated as a manufacturer’s best case rather than a measurement you can rely on across brands. Independent measurements, where the review links on a speaker’s page provide them, are worth more than the spec sheet.
What You Give Up For Efficiency
Sensitivity is not free. For a given cabinet size, a designer can have deep bass extension or high efficiency, but not both at once. The physics does not offer a way around this.
High sensitivity designs tend toward larger cabinets, larger drivers, or bass that rolls off earlier. That is why efficiency has become uncommon in modern bookshelf speakers, where compact cabinets and low bass are what sells. The speakers here that do reach the low 90s generally do so by being physically large or by using horn loading.
The full argument, along with the speakers here that manage it, is on best passive speakers for tube and low-power amplifiers.
When Sensitivity Does Not Matter Much
If you are driving speakers with a capable modern solid-state amplifier at normal domestic levels, sensitivity is close to irrelevant. Power is cheap, and the difference between an 84 dB and an 88 dB speaker is a few clicks on the volume dial.
It becomes decisive in three situations: pairing with a tube or low-power amplifier, filling a large room at high volume, or driving speakers with the modest amplifier built into an AV receiver that is also powering several other channels.
Where To Look Next
Sensitivity and impedance together determine whether a given amplifier can drive a given speaker. For what the frequency numbers alongside sensitivity mean, see frequency response explained and bass extension explained. For loudness measured as output rather than efficiency, see dB and SPL output explained.
Every passive speaker’s published sensitivity is in its spec table, across large bookshelf speakers, medium bookshelf speakers and large floorstanding speakers.
Frequently Asked Questions
What is a good speaker sensitivity? Anything from about 85 dB upward is unremarkable and works fine with a normal solid-state amplifier. Above roughly 90 dB counts as high sensitivity and starts to open up tube and low-power amplifiers as options. Below about 84 dB the speaker is power hungry and needs an amplifier with real headroom to play loudly without strain.
Does higher sensitivity mean better sound? No. Sensitivity describes efficiency, not quality. It tells you how much amplifier power the speaker needs, nothing more. Plenty of excellent speakers are inefficient by design, having traded efficiency for deeper bass from a smaller cabinet.
Why does every 3 dB matter? Because the decibel scale is logarithmic. A 3 dB increase in sensitivity halves the amplifier power needed for the same volume, and a 3 dB decrease doubles it. Small looking differences compound quickly, so a 6 dB gap represents a fourfold difference in the power required.
Is 2.83V sensitivity the same as 1W sensitivity? Only for an 8 ohm speaker. 2.83 volts delivers one watt into 8 ohms, but two watts into 4 ohms. A 4 ohm speaker rated at 2.83 volts therefore reads roughly 3 dB higher than its true one watt figure, so sensitivity is only directly comparable between speakers of the same impedance.