Calculation Result
Advanced Calculator
Choose what you want to solve. Enter the two known core values. Optional fields help estimate input demand, design margin, energy, and cost.
Example Data Table
| Case | Torque | Speed | Output Power | Use Case |
|---|---|---|---|---|
| Workshop motor | 250 Nm | 1750 RPM | 45.81 kW | Motor shaft estimate |
| High torque drive | 900 Nm | 350 RPM | 32.99 kW | Gearbox output |
| Fast spindle | 18 Nm | 6000 RPM | 11.31 kW | Machine spindle |
| Engine check | 310 lb-ft | 4200 RPM | 247.90 hp | Engine output review |
Formula Used
The core equation is: Power = Torque × Angular Speed.
When torque is in newton meters and speed is in RPM: Power watts = Torque Nm × RPM × 2π ÷ 60.
To solve torque: Torque Nm = Power watts ÷ Angular Speed.
To solve speed: RPM = Power watts × 60 ÷ (Torque Nm × 2π).
Input power is estimated as: Input Power = Output Power ÷ Efficiency. Design power is estimated as: Design Power = Output Power × Service Factor.
How to Use This Calculator
Select the value you want to calculate. Enter the two known core values. Choose matching units for torque, speed, and power. Add efficiency when you want an input demand estimate. Use service factor when the equipment must handle overload, frequent starts, heat, shock, or harsh duty.
Press the calculate button. The result appears above the form and below the header. Review the main result, converted values, energy estimate, cost estimate, and notes. Use CSV for spreadsheet records. Use PDF for reports, job files, or customer documentation.
Torque, Speed, and Power Planning Guide
Why these values matter
Torque, rpm, and power are linked measurements. They describe how a rotating system creates useful work. Torque shows twisting force. RPM shows rotational speed. Power shows the rate of work. A small motor can spin fast and still make modest power. A slow shaft can make high power when torque is strong.
Using the calculator
This calculator helps compare those values in one place. You can solve for power, torque, or speed. You can also switch between common units. This is useful for motors, engines, pumps, fans, gearboxes, dyno notes, and workshop checks. It helps avoid manual conversion mistakes.
Understanding the formula
The main relationship uses angular speed. One revolution per minute is converted to radians per second. Power in watts equals torque in newton meters multiplied by angular speed. The tool then converts the answer into kilowatts and horsepower. When torque is entered in pound feet or pound inches, it is converted before calculation.
Efficiency and service factor
Efficiency is included for practical planning. A system rarely delivers all input power to the output shaft. Belts, bearings, gears, couplings, and heat create losses. Entering efficiency helps estimate required input power. Service factor adds another margin. It can help size equipment for heavy duty use.
Energy and cost checks
The runtime and energy fields extend the result further. They estimate energy use from power and operating time. A cost field can also estimate operating cost. These outputs are not a replacement for a formal engineering review. They are helpful for quick planning and comparisons.
Better input data
For best results, use measured values from trusted tools. Enter shaft torque from a reliable gauge. Enter speed from a tachometer or controller reading. Keep units consistent. Review the notes and warnings shown with each result. High loads, low efficiency, or unrealistic speed values can indicate a sizing issue.
Reporting results
This tool is useful during early design. It also helps compare two machines. Save the CSV file for spreadsheets. Export the PDF for records, estimates, or job notes. Use the example table to test expected behavior. Change one value at a time. This makes the effect clear. Document assumptions before sharing results. Small changes in torque or speed can create large power changes at higher rotation rates during real equipment use.
FAQs
1. What does this calculator solve?
It can solve power, torque, or RPM. Choose the missing value first. Then enter the two known values with their units.
2. What is the main torque power formula?
The main formula is power equals torque multiplied by angular speed. RPM is converted to radians per second before calculation.
3. Can I use pound feet for torque?
Yes. The calculator accepts pound feet and pound inches. It converts them to newton meters internally before solving the final result.
4. What does efficiency change?
Efficiency estimates required input power. Lower efficiency means the system needs more input power to deliver the same shaft output power.
5. What is service factor?
Service factor adds design margin. It is useful for shock loads, heavy starts, heat, long duty cycles, or uncertain operating conditions.
6. Is horsepower mechanical horsepower?
The horsepower option uses standard mechanical horsepower. The metric horsepower option is also included for users who need that conversion.
7. Can this replace engineering design?
No. It supports quick estimates and comparisons. Critical machines should still be checked by qualified engineers and equipment manufacturers.
8. Why is my result very high?
High torque, high speed, low efficiency, or a large service factor can raise the result. Check units and measured inputs carefully.