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SPL Distance Calculator
Estimate how direct sound level changes with distance from a point source, with a reference-distance comparison table.
01 / Set your measurements
SPL: −20–200 dB. Distances: 0.1–1000 in the selected unit. Changing units keeps the entered numbers.
Inputs stay on this page and clear on refresh.
02 / Your result
SPL Distance Calculator
Reference SPL: 100 dB SPL Reference distance: 1 m Target distance: 10 m
- Estimated SPL
- 80.00dB SPL
- Level change
- -20.00dB
| Distance (m) | Estimated SPL (dB SPL) |
|---|---|
| 0.5 | 106.02 |
| 1 | 100.00 |
| 2 | 93.98 |
| 4 | 87.96 |
| 8 | 81.94 |
L₂ = L₁ − 20 log₁₀(r₂/r₁). Use the same distance unit and an unchanged source level. Doubling distance gives approximately −6.02 dB; halving gives +6.02 dB. The model assumes a point source in a free field, in the far field and on the same radiation axis. It excludes reflections, room reverberation, barriers, air absorption, background noise and changes in directivity. It does not predict line-array behavior, safe exposure or regulatory compliance.
Methodology
How it works
L₂ = L₁ − 20 log₁₀(r₂/r₁). Use the same distance unit and an unchanged source level. Doubling distance gives approximately −6.02 dB; halving gives +6.02 dB. The model assumes a point source in a free field, in the far field and on the same radiation axis. It excludes reflections, room reverberation, barriers, air absorption, background noise and changes in directivity. It does not predict line-array behavior, safe exposure or regulatory compliance.
Method and assumptions documented by Techrider.live
Updated September 16, 2026
Frequently asked questions
Which reference SPL should I enter?
Use a measured or specified sound pressure level at a known distance under matching conditions. Keep the same frequency weighting, bandwidth and averaging method when comparing values. Do not substitute amplifier watts or a sensitivity specification without accounting for its measurement conditions. For example, 100 dB SPL at 1 m becomes an estimated 80 dB SPL at 10 m.
Does changing metres to feet convert my inputs?
No. Changing units keeps the entered numbers. Both distances always share the selected unit, so their ratio and the calculated SPL stay the same. The table compares half, one, two, four and eight times the reference distance; these are model examples, not verified listening positions.
Will the result match the sound level at my venue?
Not necessarily. Near-field sources, arrays, reverberant rooms and obstructions can depart substantially from the model. A target closer than the reference produces a higher estimated level, but may leave the far-field conditions. Verify coverage and level with the loudspeaker manufacturer’s prediction tools and on-site measurements.