dB Calculator
Calculate decibel (dB) power ratios
How to Use This Calculator
Enter Power 1
Input the first power value (P₁) in Watts. This is typically the reference or measured power.
Enter Power 2
Input the second power value (P₂) in Watts. This is typically the reference power for comparison.
Calculate
Click calculate to get the decibel ratio: dB = 10 × log₁₀(P₁/P₂).
Formula
dB = 10 × log₁₀(P₁ / P₂)
where dB = decibels, P₁ = power 1 (W), P₂ = power 2 (W)
Example:
If P₁ = 100 W and P₂ = 10 W:
dB = 10 × log₁₀(100 / 10) = 10 × log₁₀(10)
dB = 10 × 1 = 10 dB
This means P₁ is 10 dB greater than P₂, or 10 times more powerful.
About dB Calculator
The dB Calculator converts power ratios to decibels (dB), a logarithmic unit used to express the ratio between two power values. Decibels are widely used in audio engineering, electronics, telecommunications, and acoustics to express power gains, losses, and signal levels.
When to Use This Calculator
- Audio Engineering: Calculate amplifier gains and signal levels
- Electronics: Express power ratios in circuits and systems
- Telecommunications: Measure signal strength and attenuation
- Acoustics: Compare sound power levels
- RF Engineering: Express antenna gains and transmission losses
- Audio Equipment: Understand amplifier specifications and power ratings
Why Use Our Calculator?
- ✅ Quick Conversion: Convert power ratios to dB instantly
- ✅ Accurate Results: Uses standard logarithmic formula
- ✅ Easy to Use: Simple interface for power ratio calculations
- ✅ Educational: Learn about decibels and logarithmic scales
- ✅ Free Tool: No registration required
Understanding Decibels
Decibels use a logarithmic scale to express power ratios, making it easier to work with very large or very small ratios. The decibel scale compresses large ranges into manageable numbers.
- 3 dB represents approximately a 2:1 power ratio (doubling or halving)
- 10 dB represents a 10:1 power ratio
- 20 dB represents a 100:1 power ratio
- Negative dB values indicate power loss or attenuation
- Positive dB values indicate power gain or amplification
Common dB Values
- 0 dB: Equal power (1:1 ratio)
- 3 dB: Double power (2:1 ratio)
- 6 dB: 4× power (4:1 ratio)
- 10 dB: 10× power (10:1 ratio)
- 20 dB: 100× power (100:1 ratio)
Frequently Asked Questions
What is a decibel (dB)?
A decibel is a logarithmic unit used to express the ratio between two power values. It's calculated as dB = 10 × log₁₀(P₁/P₂).
Why use decibels instead of power ratios?
Decibels compress large power ranges into manageable numbers. For example, a 1,000,000:1 ratio is simply 60 dB, making calculations and comparisons much easier.
What does 3 dB mean?
3 dB represents approximately a 2:1 power ratio. This means doubling or halving the power results in a 3 dB change.
Can dB be negative?
Yes, negative dB values indicate that P₁ is less than P₂, representing power loss or attenuation. For example, -3 dB means the power is halved.
Is this the same as voltage dB?
No, this calculator is for power ratios. For voltage ratios, the formula is dB = 20 × log₁₀(V₁/V₂) because power is proportional to voltage squared.