Decibel Calculator
Calculate decibels using dB = 10·log₁₀(P₁/P₂) for power or 20·log₁₀ for amplitude. Enter two values to compare.
How to Use the Decibel Calculator
- Enter the first value (measured or signal level).
- Enter the second value (reference level).
- Click Calculate to see decibel results for both power and amplitude ratios.
快速参考
| 从 | 到 |
|---|---|
| Ratio 2:1 (power) | 3 dB |
| Ratio 10:1 (power) | 10 dB |
| Ratio 100:1 (power) | 20 dB |
| Ratio 2:1 (amplitude) | 6 dB |
| Ratio 10:1 (amplitude) | 20 dB |
使用场景
- •Comparing audio signal levels in sound engineering.
- •Calculating amplifier gain or attenuation.
- •Measuring signal strength in telecommunications.
公式
dB (power) = 10 × log₁₀(P₁/P₂); dB (amplitude) = 20 × log₁₀(V₁/V₂).
常见问题
What is a decibel?
A decibel (dB) is a logarithmic unit expressing the ratio between two values — commonly used for sound, signal power, and gain.
When do I use 10·log vs 20·log?
Use 10·log₁₀ for power ratios and 20·log₁₀ for amplitude (voltage, pressure) ratios.
Is this calculator free?
Yes, all OhMyCalc calculators are completely free.