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RPM to Voltage Calculator

Free RPM to Voltage Calculator to convert motor speed into voltage instantly. Accurate formulas, step-by-step solution, and easy online conversion tool.

Formulas Used
Eb = Kb × RPM
or
Voltage = RPM ÷ Kv
RPM
V/RPM
A
Ω

Understanding the relationship between RPM and voltage is very important when working with electric motors, generators, and mechanical systems. Whether you are a student, engineer, technician, or hobbyist, knowing how to convert RPM into voltage helps you design better systems and avoid performance problems.

That is why we developed this RPM to Voltage Calculator. This free online tool allows users to easily calculate voltage from RPM using accurate scientific formulas. It works for DC motors, BLDC motors, and generators. With simple inputs, you can get instant and reliable results without doing manual calculations.

Our RPM to Voltage calculator is designed to be fast, accurate, and beginner-friendly, so anyone can use it without technical difficulty.

How Is RPM Related to Voltage?

RPM means revolutions per minute. It shows how fast a motor shaft is rotating. Voltage, on the other hand, represents electrical potential.

In electric motors and generators, RPM and voltage are directly related. When a motor spins faster, it generates more back EMF, which increases voltage. When the speed decreases, voltage also decreases.

This relationship is based on Faraday’s Law of electromagnetic induction. As the motor rotates, it cuts magnetic fields and produces electrical energy. The faster the rotation, the higher the voltage.

In most practical cases, RPM and voltage have a linear relationship, meaning when RPM doubles, voltage also doubles, if other conditions remain constant.

How to Calculate RPM from Voltage?

If you know the motor speed constant, you can easily calculate RPM from voltage.

The basic formula is:

RPM = Kv × Voltage

Here, Kv is the speed constant of the motor in RPM per volt.

For example, if a motor has a Kv rating of 800 RPM/V and the applied voltage is 12V, then:

RPM = 800 × 12

RPM = 9600

So, the motor will rotate at about 9600 RPM.

This formula is commonly used for BLDC motors and RC motors.

RPM to Voltage Formula

The most accurate RPM to voltage formula depends on the motor constant type.

When Kb is given in volts per RPM:

Eb = Kb × RPM

When Kv is given in RPM per volt:

Eb = RPM ÷ Kv

When Kb is given in volts per radian per second:

ω = (2 × π × RPM) ÷ 60

Eb = Kb × ω

Where:

  • Eb = Back EMF voltage
  • Kb = Back EMF constant
  • Kv = Speed constant
  • RPM = Revolutions per minute
  • ω = Angular speed in rad/s

For real motors with losses:

V = Eb + (Ia × Ra)

Where:

  • Ia = Armature current
  • Ra = Armature resistance

This formula gives the actual terminal voltage.

How to Convert RPM into Power?

RPM alone cannot calculate power. You also need torque.

The power formula is:

Power = Torque × Angular Speed

First convert RPM to rad/s:

ω = (2 × π × RPM) ÷ 60

Then:

Power = Torque × ω

So, to convert RPM into power, you must know the motor torque value.

How to Use Online RPM to Voltage Calculator

  1. Open the RPM to Voltage Calculator on our website.
  2. Enter the motor speed in RPM.
  3. Select the calculation method. Choose Kb, Kv, or rad/s based on your motor data.
  4. Enter the motor constant value from the datasheet.
  5. If available, enter armature current and resistance for better accuracy.
  6. Click the Calculate button.

View the voltage result and step-by-step solution.

This process takes only a few seconds and gives instant results.

Example RPM to Voltage Calculation

Let us understand with a simple example.

Given:

RPM = 3000

Kb = 0.02 V/RPM

Formula:

Eb = Kb × RPM

Calculation:

Eb = 0.02 × 3000

Eb = 60 V

So, the back EMF voltage is 60 volts.

Now, if:

Ia = 2 A

Ra = 1.5 Ω

Voltage drop = Ia × Ra

Voltage drop = 2 × 1.5

Voltage drop = 3 V

Applied voltage:

V = Eb + Voltage drop

V = 60 + 3

V = 63 V

So, the final terminal voltage is 63 volts.

What Is 1 RPM Equal To?

1 RPM means one full rotation in one minute.

In other units:

1 RPM = 0.01667 revolutions per second

1 RPM = 0.1047 rad/s

It does not directly equal voltage or power. It only represents speed. Voltage depends on motor design and constants.

Benefits of Our RPM to Voltage Calculator

Our calculator offers accurate scientific formulas. It supports multiple motor constants. It provides step-by-step explanations. It works for DC, BLDC, and generator systems. It is mobile friendly and free to use. It is designed for students, professionals, and beginners.

Because of these features, it is one of the most reliable online RPM to voltage conversion tools.

Final Verdict

The RPM to Voltage Calculator is a powerful and easy tool for converting motor speed into electrical voltage. It uses industry-standard formulas and real-world corrections to give accurate results.

Whether you are working on electronics projects, motor design, robotics, or renewable energy systems, this calculator saves time and avoids calculation mistakes.

If you want fast, simple, and reliable RPM to voltage conversion, this tool is the perfect solution.

FAQs

How is RPM related to voltage?

RPM and voltage are directly proportional in most motors. Higher RPM produces higher back EMF voltage.

Can I calculate voltage from RPM without motor constant?

No. You must know Kb or Kv from the motor datasheet to get accurate results.

Is this calculator suitable for BLDC motors?

Yes. It supports Kv-based calculations for BLDC and RC motors.

Does this tool consider power losses?

Yes. When current and resistance are entered, it calculates voltage drop.

Can I use this calculator for generators?

Yes. It works for generators because they also produce voltage from rotation.