Speaker SPL Calculator
Predicting a speaker's output SPL is straightforward once you know two things: its sensitivity rating (dB SPL at 1 W / 1 m) and the amplifier power driving it. Every 10-fold increase in power adds 10 dB, so the formula is SPL = sensitivity + 10 log10(power). A speaker rated 90 dB/W/m driven by 100 W produces 90 + 20 = 110 dB at 1 metre. From there, apply the inverse square law to find the level at any other distance. This calculator is useful for live sound system design, home theatre planning, and checking compliance with OSHA and NIOSH noise exposure limits.
Speaker SPL formula
SPL = Sensitivity + 10 × log10(Power)
Where sensitivity is in dB/W/m and power is in watts. The result is the SPL in dB at 1 metre on axis in free field.
Understanding the result
- The result is the on-axis SPL at exactly 1 metre in an anechoic free-field condition.
- For other distances, subtract 20 log10(d) dB where d is distance in metres.
- Room gain will add several dB in a typical enclosed space.
- OSHA permissible exposure at 90 dB is 8 hours; at 100 dB it drops to 2 hours.
Frequently asked questions
What is speaker sensitivity?
Speaker sensitivity is the SPL produced at 1 metre when driven with 1 watt of power, measured on axis in an anechoic environment. Typical values range from 85 dB/W/m for studio monitors to 100 dB/W/m for efficient PA drivers.
How does power affect SPL?
Each doubling of power adds 3 dB. The formula is SPL = sensitivity + 10 log10(power in watts). To gain 10 dB more than the 1 W sensitivity rating, you need 10 W; for 20 dB more you need 100 W.
Does this account for distance?
Sensitivity is rated at 1 metre. For other distances, subtract 20 log10(distance in metres) from the result to apply the inverse square law. At 10 m, subtract 20 dB from the 1 m result.
What is program vs continuous power?
Amplifier continuous (RMS) power drives the steady-state SPL calculation. Program power is typically 2x the continuous rating and is used for brief dynamic peaks. Use continuous power here for average SPL.
Why do multiple speakers add less than expected?
Two identical speakers add 3 dB (doubling power into same directivity), not 6 dB. Array gain in coherent coupling scenarios can be higher, but the simple power-doubling rule applies for incoherent (uncorrelated) sources.
Official sources
- Audio Engineering Society (AES): aes.org.
- OSHA: Occupational Noise Exposure.
- OpenStax University Physics Vol. 1, Chapter 17: Sound.
Reviewed by the CalculatorHub team, edited by James Graham, 15 June 2026. See our methodology.