What is the reference intensity (I₀)?

The standard reference intensity is 1×10⁻¹² W/m², which corresponds approximately to the threshold of human hearing at 1 kHz. All dB SPL values are relative to this reference.

How does sound level change with distance?

For a point source in free field, intensity follows the inverse-square law: doubling the distance reduces intensity by a factor of 4, which is a drop of about 6 dB.

What is the difference between dB SPL and dB SIL?

dB SPL (Sound Pressure Level) uses a pressure reference of 20 µPa, while dB SIL (Sound Intensity Level) uses 10⁻¹² W/m². For plane waves in air they are numerically equal, so this calculator applies to both.

What is a safe sound level?

Prolonged exposure above 85 dB can cause hearing damage. Brief exposure to levels above 120 dB may cause immediate harm. Normal conversation is around 60 dB.

Can I calculate intensity from a directional source?

The Power → dB mode assumes an omnidirectional point source. For a directional source, divide the total power by the solid angle in steradians before using the intensity mode.

Sound Intensity Calculator

Name: Sound Intensity Calculator
Availability: InStock
Author: Nham Vu

Calculate sound intensity level (dB) from acoustic power and area, or convert between intensity (W/m²) and dB SPL.

Sound Intensity Calculator

Calculation Mode

Power & Distance → dB

Acoustic power (W) + distance (m) → dB SPL

Intensity → dB

Intensity (W/m²) → dB SPL

dB → Intensity

dB SPL → intensity (W/m²)

Acoustic Power (W)

Total acoustic power output of the source

Distance (m)

Distance from the point source

Result

Enter values and click Calculate

Common Sound Levels

Source	dB SPL	Intensity (W/m²)
Threshold of hearing	0	1.0×10⁻¹²
Rustling leaves	20	1.0×10⁻¹⁰
Quiet library	40	1.0×10⁻⁸
Normal conversation	60	1.0×10⁻⁶
Busy traffic	80	1.0×10⁻⁴
Lawn mower	90	1.0×10⁻³
Rock concert	110	1.0×10⁻¹
Threshold of pain	120–130	1–10
Jet engine (30 m)	150	1.0×10³

Summary

Calculate sound intensity level (dB) from acoustic power and area, or convert between intensity (W/m²) and dB SPL.

How it works

Choose a calculation mode: Power → dB, Intensity → dB, or dB → Intensity.
Enter the required values (power in watts, distance in meters, or intensity in W/m²).
Click Calculate to see the result instantly.
Use the reference table to compare your result with common sound levels.
Results are computed using the standard formula: L = 10 × log₁₀(I / I₀).

Use cases

Estimate dB levels from a speaker or loudspeaker at a given distance.
Check whether a work environment exceeds safe noise exposure limits.
Convert measured intensity readings to dB SPL for comparison.
Understand how sound level drops with distance (inverse-square law).
Study acoustic physics for exams or professional certifications.
Verify engineering calculations for noise control projects.

Frequently Asked Questions

Last updated: 2026-06-15 · Reviewed by Nham Vu