Decibel Distance Calculator
Enter your horn's dB at source plus a distance — see how loud it actually is for a pedestrian. Based on the inverse-square law. Embeddable.
150dB
The rated output on the horn's spec sheet
90160
100ft
How far away the listener is
101000
At 100 ft, you'll hear
~130dB
Roughly the same as: Jackhammer (close) (130 dB)
Ring chart
Rings show how dB drops with distance around the source. The dashed circle marks your chosen distance.
Where it sits on the scale
130 dB
30 dB · whisper100 · subway120 · jet takeoff160 dB · gunshot
The OSHA permanent damage threshold starts at 85 dB with long exposure and drops to seconds at 110+ dB.
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Drop this calculator on your forum post, blog, or build thread. The embed keeps the current values.
Frequently asked
- Why does sound get quieter with distance?
- Sound energy spreads out over a larger area as it travels. The inverse-square law predicts a 6 dB drop for every doubling of distance in free field (no reflections). This calculator uses that formula with 10 ft as the reference distance — the standard for horn dB ratings.
- Is 150 dB safe?
- No. 150 dB can cause instant, permanent hearing damage at close range. OSHA's exposure ceiling for impulse noise is 140 dB peak. Always fire your horn in open areas with no pedestrians nearby, and wear hearing protection when testing.
- What's the loudest legal train horn?
- There is no federal decibel limit on aftermarket auto horns, but most states cap at 95–110 dB measured at a fixed distance (commonly 50 ft). See our state-by-state legality pages for the specific statute that applies to you.
- Why 10 ft as the reference distance?
- Ten feet is the industry-standard distance for rating aftermarket train horns. Manufacturers publish dB at 10 ft, so comparisons stay apples-to-apples. We use the same reference so our calculator matches the number printed on the box.
- Does this account for reflections or indoor spaces?
- No. The inverse-square law is for free-field (open air) propagation. Indoors, reflections off walls and the ground can make dB higher at the same distance. Treat our numbers as a realistic outdoor lower bound.
- Can I embed this calculator on my forum or blog?
- Yes. Use the iframe embed code in the Share section — values auto-populate from the sliders. Attribution is appreciated but not required.
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