Op Amp Output Voltage Calculator

Calculator

Circuit mode

Single input Vin, V

Non-inverting input V+, V

Inverting input V-, V

Reference voltage Vref, V

Input resistor Rin, ohms

Feedback resistor Rf, ohms

Ground resistor Rg, ohms

Custom closed-loop gain

Open-loop gain Aol

Positive supply rail, V

Negative supply rail, V

Positive rail headroom, V

Negative rail headroom, V

Input offset voltage, mV

Input bias current, nA

CMRR, dB

Signal frequency, Hz

Gain bandwidth product, MHz

Load resistance, ohms

Summing inputs, volts

Formula Used

Non-inverting amplifier: Vout = Vref + (1 + Rf / Rg) × (Vin - Vref)

Inverting amplifier: Vout = Vref - (Rf / Rin) × (Vin - Vref)

Differential amplifier: Vout = Vref + (Rf / Rin) × (V+ - V-)

Inverting summing amplifier: Vout = Vref - Rf × Σ((Vi - Vref) / Rin)

Comparator: Vout = Vref + Aol × (V+ - V-)

Output clipping: Final Vout = limited value between output swing limits

Slew rate: SR = 2π × frequency × output amplitude

Bandwidth estimate: Closed-loop bandwidth = GBW / noise gain

How to Use This Calculator

Select the circuit mode that matches your op amp connection.
Enter input voltages and reference voltage.
Add resistor values for gain calculation.
Enter supply rails and output headroom limits.
Add offset voltage, bias current, and CMRR if known.
Enter frequency, gain bandwidth product, and load resistance.
Click calculate to view the final output voltage.
Use CSV or PDF buttons to save the result.

Example Data Table

Mode	Inputs	Resistors	Supply	Expected behavior
Non-inverting	Vin = 1 V, Vref = 0 V	Rf = 10 kΩ, Rg = 10 kΩ	±15 V, 1.5 V headroom	Ideal output is about 2 V.
Inverting	Vin = 1 V, Vref = 0 V	Rf = 20 kΩ, Rin = 10 kΩ	±12 V, 1 V headroom	Ideal output is about -2 V.
Differential	V+ = 1.2 V, V- = 1 V	Rf = 100 kΩ, Rin = 10 kΩ	0 V to 5 V	Output may clip if headroom is high.
Summing	0.5 V, 1 V, 1.5 V	Rf = 10 kΩ, Rin = 10 kΩ	±15 V	Ideal output is about -3 V.

Op Amp Output Voltage Design Notes

Why Output Voltage Matters

Output voltage is the main result of an op amp stage. It tells you how the circuit will drive the next block. A perfect design stays inside the supply rails. A real design also respects swing limits, offset voltage, bias current, bandwidth, and load current.

Practical Amplifier Modeling

This calculator treats the op amp as a practical building block. You can choose common amplifier modes. You can test non-inverting gain, inverting gain, differential gain, summing action, comparator action, or a custom closed-loop gain. Each option uses the matching voltage equation. Then the tool adds practical error terms. These terms help you see why a measured output can differ from the ideal value.

Rail Limits and Clipping

Supply rails are important. Many op amps cannot reach both rails. The positive and negative headroom fields model this behavior. The calculator clips the predicted output to the allowed swing range. It also reports the remaining output margin. This makes the result useful for low voltage circuits and sensor interfaces.

Error and Speed Checks

Offset voltage is modeled as an input error multiplied by noise gain. Input bias current is modeled as a feedback resistor voltage error. CMRR error is estimated from the common-mode voltage. These checks are approximate. They are still helpful during early design.

Speed also matters. A sine output needs enough slew rate. The calculator estimates the required slew rate from output amplitude and frequency. It also estimates closed-loop bandwidth from gain bandwidth product. These values show whether the selected op amp can follow the signal without major distortion.

Load and Final Review

Load current is another practical limit. Low resistance loads can pull high current from the output pin. The calculator estimates load current and load power. You can compare these values with the device data sheet.

Use the result as a design guide. It is not a replacement for bench testing. Real circuits may include input range limits, output short circuit limits, noise, temperature drift, and stability issues. Always confirm critical designs with simulation, data sheets, and measurements. This approach gives a faster path from equation to working circuit. For best results, enter resistor values in ohms and voltages in volts. Keep units consistent. Review clipping first. Then review error, speed, and loading results before choosing parts. This prevents many early circuit design mistakes.

FAQs

What is op amp output voltage?

It is the voltage produced at the output pin. It depends on input voltage, feedback network, reference voltage, supply rails, and practical op amp limits.

Why does the output clip?

Output clipping happens when the calculated voltage is outside the allowed output swing. The supply rails and output headroom decide this limit.

What is noise gain?

Noise gain is the gain applied to input-referred errors. Offset voltage and some noise sources are multiplied by this value.

Can this calculator handle single-supply op amps?

Yes. Enter the negative rail as 0 V and the positive rail as the supply voltage. Add realistic headroom values for the selected device.

What is the use of Vref?

Vref shifts the output around a reference level. It is useful in single-supply circuits, biased sensor stages, and level-shifting amplifier designs.

Why include input bias current?

Input bias current creates small voltage errors through resistors. The error becomes more important when feedback resistance is high.

How is slew rate estimated?

The calculator uses sine wave behavior. It estimates slew rate from signal frequency and output amplitude using SR = 2πfVpeak.

Is this result exact for every op amp?

No. It is a design estimate. Always check the data sheet for input range, output swing, load current, stability, and temperature limits.