Sound Distance Calculator
Estimate how loud a sound will be at any distance from the source
Sound gets quieter as you move away from its source — but by how much? In open air, sound intensity follows the inverse square law: every time you double the distance, the sound pressure level drops by approximately 6 dB. A jackhammer that measures 100 dB at 1 meter will be around 80 dB at 10 meters and roughly 60 dB at 100 meters.
Use this calculator to estimate noise levels at any distance. It's useful for understanding construction noise, traffic levels, speaker placement, or how far you need to be from a loud source to be safe. For a full reference of common sound levels, see the decibel level chart.
Distance Noise Calculator
Quick presets:
Estimated level at 10 m
80.0 dB
Loud
Reduction from source: 20.0 dB over 10 m
How 100 dB Changes With Distance
Sound pressure drops by ~6 dB each time the distance doubles (inverse square law in free-field conditions).
| Distance | Level | Reduction | Risk |
|---|---|---|---|
| 1 m | 100.0 dB | −0.0 dB | Hazardous |
| 2 m | 94.0 dB | −6.0 dB | Loud |
| 4 m | 88.0 dB | −12.0 dB | Loud |
| 8 m | 81.9 dB | −18.1 dB | Loud |
| 16 m | 75.9 dB | −24.1 dB | Moderate |
| 32 m | 69.9 dB | −30.1 dB | Moderate |
| 64 m | 63.9 dB | −36.1 dB | Moderate |
How Sound Propagation Works
In open air with no obstacles, sound radiates outward from a point source in all directions. As it spreads, the same energy covers a larger area, and the sound pressure level decreases. This relationship is described by the inverse square law:
L₂ = L₁ − 20 × log₁₀(d₂ / d₁)
Where L₁ is the source level, d₁ is the reference distance, and d₂ is the listener distance
This means sound drops by 6 dB every time the distance doubles. In practice, this is an idealized model — indoors, reflections from walls, ceilings, and floors reduce the attenuation to approximately 3–4 dB per doubling. Outdoors, wind, temperature gradients, ground absorption, and barriers like buildings also affect the result.
For line sources like highways or railways, the geometry is different: sound drops by approximately 3 dB per doubling of distance instead of 6 dB, because the source extends along a line rather than emanating from a single point.
Practical Examples
Construction site
A jackhammer at 100 dB measured at 1 m drops to about 74 dB at 5 m and 60 dB at 30 m — roughly the level of normal conversation.
Construction noise guideConcert speakers
Front-row levels of 110 dB drop to roughly 90 dB at 10 m, still loud enough to cause damage within 2 hours of exposure.
Concert noise levelsHighway traffic
Traffic at 85 dB drops to about 65 dB at 50 m and 55 dB at 150 m. Note: highways act as line sources, so actual reduction is less than calculated.
Traffic noise guideDog barking
A loud bark at 85 dB from 1 m drops to roughly 65 dB at 10 m — still clearly audible but no longer a hearing risk.
Dog bark noise levelsWhen Should You Be Concerned?
Use the calculator to check whether you're at a safe distance from a noise source. As a rule of thumb: if the estimated level at your position exceeds 85 dB, you should either move further away or wear hearing protection. At 100 dB, safe exposure drops to just 15 minutes.
Keep in mind that this calculator models ideal free-field conditions. Real-world results depend on your environment — use the noise meter tool to measure actual sound levels at your position. For detailed exposure limits, see the decibel level chart.
Frequently Asked Questions
How does sound decrease with distance?
In open air, sound intensity follows the inverse square law — sound pressure drops by approximately 6 dB each time you double the distance from the source. Indoors, reflections reduce this effect.
Does the 6 dB rule always apply?
The 6 dB per doubling rule applies to point sources in free-field conditions (outdoors, no reflections). Indoors, hard surfaces reflect sound and the drop may be only 3–4 dB per doubling. Line sources like highways drop by about 3 dB per doubling.
How far away can you hear 100 dB?
A 100 dB source measured at 1 meter would drop to roughly 60 dB at about 100 meters in open air — still clearly audible. It would reach near-silence (~20 dB) at approximately 10 km under ideal conditions, though wind, terrain, and obstacles reduce this significantly.
Is this calculator accurate for indoor use?
This calculator models free-field (outdoor) propagation. Indoor environments have reflections that keep sound levels higher. Use it as a starting estimate, then measure the actual level with a noise meter for accuracy.
Want to Measure the Actual Sound Level?
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