Interactive Amplifier Calculator
Use these quick tools to calculate amplifier gain, convert gain to and from decibels, estimate non-inverting op-amp gain, and compute output power into a load.
1) Voltage Gain from Input and Output
2) Convert Gain (dB) to Linear Voltage Gain
3) Non-Inverting Op-Amp Gain
4) Output Power into Load
How to Use This Amplifier Calculator
This amplifier calculator is designed for quick, practical electronics work. Whether you are building an audio preamp, checking a power amp stage, or choosing resistor values for an op-amp, these tools help you move from guesswork to clear numbers.
The calculator covers four common tasks: finding linear voltage gain, converting gain to decibels, calculating non-inverting op-amp gain, and estimating power delivered to a load. These are the exact calculations most hobbyists and engineers repeat over and over in design and troubleshooting.
Core Amplifier Formulas (Quick Reference)
- Voltage Gain (linear): Av = Vout / Vin
- Voltage Gain in dB: Gain(dB) = 20 × log10(Av)
- dB to Linear Gain: Av = 10^(dB/20)
- Non-Inverting Op-Amp: Av = 1 + (Rf / Rg)
- Output Power: P = V² / R
- Output Current: I = V / R
Why dB Matters in Amplifier Design
Linear gain tells you the simple multiplication factor (for example, 20×). Decibels tell you gain on a logarithmic scale, which matches how signal levels are often discussed in audio and RF work. A linear gain of 10 equals 20 dB, while a gain of 100 equals 40 dB. This makes dB ideal for cascading multiple stages and comparing system behavior.
Example: Fast Gain Check
If your input is 100 mV and output is 2 V, then Av = 2 / 0.1 = 20. In decibels, that is 20 × log10(20) ≈ 26.02 dB. This is a typical preamplifier-level voltage gain.
Choosing Gain for Real Systems
Audio Preamps
Microphone and instrument sources are often small, so preamps commonly need moderate to high gain. The right amount depends on source level, noise floor, and the next stage's required input voltage.
Power Amplifiers
Power stages are usually evaluated by both gain and load performance. Even if voltage gain is correct, output power depends on supply rails, load impedance, thermal limits, and distortion constraints.
Op-Amp Stages
For non-inverting designs, resistor ratio sets gain directly. If you choose Rf = 47kΩ and Rg = 2.2kΩ, gain is 1 + 47000/2200 ≈ 22.36 (about 27 dB). This calculator gives that instantly so you can iterate quickly.
Common Mistakes to Avoid
- Mixing peak and RMS values: Use consistent voltage type when computing gain and power.
- Using 10 log instead of 20 log for voltage gain: 20 log is correct for voltage ratios.
- Ignoring load impedance: Output power can change drastically with speaker/load resistance.
- Overlooking headroom: Calculated gain may clip if supply rails are too low.
- Dividing by zero or near-zero inputs: Extremely small Vin creates unrealistic gain numbers.
Practical Design Workflow
- Estimate required output voltage for your target load and loudness/signal level.
- Use the gain calculator to determine required stage gain from available input.
- Convert between linear and dB to match datasheets and measurement tools.
- Pick resistor values for op-amp implementation and verify expected gain.
- Check output power/current against component ratings and thermal limits.
Final Notes
This page gives fast first-pass calculations. For production designs, also evaluate bandwidth, phase margin, distortion, noise, power supply rejection, and thermal behavior. Still, solid gain and power math is the foundation—and this amplifier calculator is built to make those fundamentals quick and reliable.