Practical tools for measured work
Amplifier Power & Speaker SPL Calculator
Estimate listening-position SPL and reverse-calculate watts per speaker for a target plus headroom.
Power is continuous watts per active speaker. The multi-speaker gain assumes coherent equal sources, which is an upper-bound simplification outside tightly matched positions.
How it works
How to use it: use a measured or manufacturer sensitivity referenced to 1 W at 1 m, then enter distance, power and an explicit room-gain assumption.
Formula. SPL = sensitivity + 10 log10(power) - 20 log10(distance) + source gain + room gain.
Example. One 88 dB speaker at 100 W and 3 m produces about 98.5 dB before room gain.
Current-input example
The result above uses these exact values. This snapshot is included when the page is printed so the output can be checked against the original measurements.
- Sensitivity (1 W/1 m)
- 88 dB
- Power per speaker
- 100 W
- Listening distance
- 3 m
- Speakers reproducing the same signal
- 2
- Assumed room gain
- 3 dB
- Target SPL
- 100 dB
- Headroom
- 3 dB
Primary result: Estimated SPL: 104.5 dB.
Before using the result
- Measure from the datum or reference edge described by this tool, and do not mix inside, outside and centerline dimensions.
- Keep inputs in the displayed units and preserve more precision than the final cutting or purchasing tolerance requires.
- When the result is close to a limit, verify it with a test piece, field measurement, manufacturer drawing or qualified project professional.
Limitations
This is a broadband free-field estimate. Impedance, compression, clipping, frequency response, boundary effects, crest factor and speaker power handling can dominate. Do not size equipment from this result without manufacturer limits.
Frequently asked questions
Does double power add 3 dB?
Ideally, yes. Real speakers may add less at high output because of thermal and mechanical compression.
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