📢 SPL (Loudness) Calculator
Estimate how loud a speaker plays from its sensitivity, power, and your distance — sound pressure level in dB, the power and distance terms broken out, and a real-world loudness reference.
📢 Estimated SPL
Loud rock concert / chainsaw — limit exposure to minutes.
Every doubling of power adds +3 dB and 10× the power adds +10 dB; distance costs −6 dB each time it doubles. Cabin gain makes real in-car SPL higher — treat this as a relative guide, and protect your hearing above 85 dB.
See where your loudness comes from
Loudness isn't just about watts. A speaker's sensitivity sets its starting point, power adds only 3 dB per doubling, and distance quietly takes some back. Seeing those three terms together explains why a more sensitive driver often beats a bigger amp, and why chasing volume with power alone hits diminishing returns fast.
Pair it with the Amplifier Power Calculator to see how much clean power you actually need, and the Crossover Calculator to send each driver the band it plays loudest and cleanest.
❓ Frequently Asked Questions
How is SPL calculated?
SPL = sensitivity (dB at 1 W / 1 m) + 10 × log₁₀(power in watts) − 20 × log₁₀(distance in metres). The power term adds loudness for the wattage you feed the speaker, and the distance term subtracts the natural spreading loss as you move away. A 90 dB speaker on 100 W at 1 m gives 90 + 20 − 0 = 110 dB.
Why does doubling power only add 3 dB?
Because loudness in decibels is logarithmic. Ten times log₁₀(2) is about 3, so every doubling of power adds roughly 3 dB, and it takes ten times the power to add 10 dB. That's why a speaker's sensitivity matters so much: a driver 3 dB more sensitive is as loud on half the power, which is far cheaper than doubling amplifier wattage to chase volume.
How much does distance reduce loudness?
In a free field, SPL falls 6 dB for every doubling of distance from the 1-metre reference (20 × log₁₀ of the distance). Inside a car this is offset by 'cabin gain' — the sealed space reinforces low frequencies — so real in-car SPL, especially bass, is usually higher than the free-field figure. Treat the result as a relative comparison tool rather than an exact in-car reading.
What SPL levels are dangerous?
Sustained exposure above about 85 dB can damage hearing over time, and the risk climbs fast: around 100 dB is very loud, 110–120 dB is concert-to-painful, and 130 dB is the threshold of pain with immediate risk. Car audio systems easily reach these levels — keep the volume in check and limit how long you listen loud.