dB Gain Calculator
Calculate amplifier gain in decibels
How to Use This Calculator
Enter Input Power
Input the power entering the amplifier (Pᵢₙ) in Watts. This is the power before amplification.
Enter Output Power
Input the power leaving the amplifier (Pₒᵤₜ) in Watts. This is the amplified power.
Calculate
Click calculate to get the gain in decibels: G(dB) = 10 × log₁₀(Pₒᵤₜ/Pᵢₙ).
Formula
G(dB) = 10 × log₁₀(Pₒᵤₜ / Pᵢₙ)
where G(dB) = gain in decibels, Pₒᵤₜ = output power (W), Pᵢₙ = input power (W)
Example:
If input power is 0.001 W and output power is 10 W:
G(dB) = 10 × log₁₀(10 / 0.001) = 10 × log₁₀(10,000)
G(dB) = 10 × 4 = 40 dB
This means the amplifier provides 40 dB of gain, or multiplies the power by 10,000.
About dB Gain Calculator
The dB Gain Calculator determines the gain of an amplifier in decibels by comparing the output power to the input power. Gain is a fundamental specification for amplifiers, indicating how much the amplifier increases the signal power.
When to Use This Calculator
- Audio Engineering: Calculate amplifier gains for audio systems
- RF Engineering: Determine gain of RF amplifiers and transmitters
- Electronics Design: Specify amplifier performance requirements
- Audio Equipment: Understand amplifier specifications and ratings
- System Design: Calculate total system gain from multiple stages
- Education: Learn about amplifier gain and decibel calculations
Why Use Our Calculator?
- ✅ Quick Calculations: Get gain in dB instantly
- ✅ Accurate Results: Uses standard logarithmic formula
- ✅ Easy Interface: Simple input/output power comparison
- ✅ Educational: Learn about amplifier gain concepts
- ✅ Free Tool: No registration required
Understanding Amplifier Gain
Amplifier gain measures how much an amplifier increases signal power. It's typically expressed in decibels (dB) because it provides a logarithmic scale that's easier to work with than large power ratios.
- Positive gain (dB) means the amplifier increases power
- Negative gain (dB) means the amplifier decreases power (loss or attenuation)
- 0 dB gain means no change in power (1:1 ratio)
- Higher dB values indicate more amplification
- Gain is usually specified at a particular frequency or bandwidth
Common Gain Values
- 0 dB: Unity gain (no amplification)
- 20 dB: 100× power amplification
- 40 dB: 10,000× power amplification
- 60 dB: 1,000,000× power amplification
- Audio Amplifiers: Typically 20-60 dB gain
Frequently Asked Questions
What is amplifier gain?
Amplifier gain is the ratio of output power to input power, expressed in decibels. It measures how much an amplifier increases signal power: G(dB) = 10 × log₁₀(Pₒᵤₜ/Pᵢₙ).
What's the difference between power gain and voltage gain?
Power gain uses the formula G(dB) = 10 × log₁₀(Pₒᵤₜ/Pᵢₙ), while voltage gain uses G(dB) = 20 × log₁₀(Vₒᵤₜ/Vᵢₙ) because power is proportional to voltage squared.
Can gain be negative?
Yes, negative gain indicates the output power is less than input power, meaning the amplifier attenuates the signal rather than amplifies it. This is called loss or attenuation.
What is a typical amplifier gain?
Typical audio amplifier gains range from 20-60 dB, corresponding to 100× to 1,000,000× power amplification. RF amplifiers may have gains from 10-40 dB depending on application.
How do I calculate total gain for multiple amplifiers?
For amplifiers in series, add their dB gains together. For example, if you have 20 dB and 30 dB amplifiers in series, the total gain is 50 dB.