Decibel (dB) Sound Level Calculator
Calculate sound pressure level in decibels from intensity or convert dB to intensity.
🔊 Physics📐 L = 10 × log₁₀(I/I₀) dB
Sound intensity (W/m²) or 0
Decibel level (dB) or 0
Please enter valid values.
Formula & Reference
| Variable | Formula | Units |
|---|---|---|
| Decibel (dB) Sound Level Calculator | L = 10 × log₁₀(I/I₀) dB | decibels |
Step-by-Step Examples
Example 1
Normal Conversation
Intensity 1e-6 W/m².
- L = 10×log10(1e-6/1e-12) = 10×6 = 60 dB
✓ 60 dB
Example 2
Jet Engine
Intensity 1 W/m².
- L = 10×log10(1/1e-12) = 120 dB — pain threshold
✓ 120 dB
Example 3
Convert 85 dB
How intense is 85 dB?
- I = 1e-12 × 10^(85/10) = 3.16e-4 W/m²
✓ 3.16×10⁻⁴ W/m²
Real-World Applications
Acoustic Engineers
Calculate and convert sound levels.
Musicians
Understand safe listening levels.
Industrial Safety
Calculate noise exposure for OSHA compliance.
Physics Students
Learn logarithmic intensity scales.
Common Mistakes to Avoid
⚠️
dB is not linear
Every +10 dB = 10× more intense. +3 dB ≈ 2×. 90 dB is NOT twice as loud as 45 dB — it's 30 million times more intense.
⚠️
Wrong reference level
Standard I₀ = 10⁻¹² W/m². Electronics uses dBm (reference 1 mW) — don't confuse them.
Frequently Asked Questions
Common dB levels? ▾
0: threshold of hearing. 30: quiet bedroom. 60: conversation. 85: heavy traffic. 100: motorcycle. 120: pain threshold.
When does hearing damage occur? ▾
85 dB sustained. OSHA: 90 dB max for 8 hours.
Why is dB logarithmic? ▾
Human hearing spans 10¹² in intensity. Log scale matches our perception.