Compute shaft power, torque, and speed from inputs. Check design torque, units, and machine behavior. Export clear reports for practical engineering review and planning.
Enter any two main values. Leave one blank to solve it.
Power in watts: P = T × 2π × RPM ÷ 60
Torque in newton meters: T = P × 60 ÷ (2π × RPM)
Speed in RPM: RPM = P × 60 ÷ (2π × T)
Angular velocity: ω = 2π × RPM ÷ 60
Design torque: Design Torque = Shaft Torque × Service Factor
Required input power: Input Power = Shaft Power ÷ Efficiency Ratio
Unit conversions: 1 hp = 745.699872 W, 1 lb-ft = 1.3558179483 Nm
| Case | Power | Torque | RPM | Use Case |
|---|---|---|---|---|
| Motor A | 15.00 kW | 150.00 Nm | 954.93 | Gear drive check |
| Motor B | 5.50 kW | 36.47 Nm | 1440.00 | Pump shaft review |
| Engine C | 3.00 hp | 9.01 lb-ft | 1750.00 | Bench test estimate |
| Drive D | 22.00 kW | 210.09 Nm | 1000.00 | Coupling selection |
This calculator helps engineers connect shaft power, torque, and rotational speed. These values define how rotating systems perform. Motors, pumps, gearboxes, fans, conveyors, and test rigs all rely on this relationship. When one value changes, the others respond. Quick calculations reduce design mistakes. They also improve equipment selection.
Power shows how fast work is done. Torque shows turning force. RPM shows rotational speed. A slow mixer can deliver high torque with modest speed. A small grinder can run at very high speed with lower torque. Designers need the right balance for durability, efficiency, and output quality.
You can use this tool during concept design, machine review, or maintenance checks. It helps estimate missing shaft values from field readings. It also supports motor sizing, drive matching, coupler selection, and gearbox verification. The added unit conversion options reduce manual rework. Export tools support reporting and documentation.
The calculator converts entered units into a common engineering base. It then solves the missing variable using the standard rotating power equation. It also estimates angular velocity, design torque, and corrected power when efficiency or service factors are included. That makes the output useful for practical sizing, not just textbook calculations.
Engineers often know motor speed and rated torque but need power. In other cases, they know power and speed and must estimate torque at the shaft. Field technicians may measure RPM and compare results with expected torque limits. Students can also use the tool to understand how rotational variables interact in real machines.
Results appear above the form for quick review. A summary table shows converted values in common units. The chart visualizes how power changes with RPM when torque stays constant. CSV and PDF exports make sharing easier. The example table below also helps users validate inputs before running live machine calculations.
Careful unit handling is essential. Confusing horsepower with kilowatts, or pound-feet with newton-meters, can distort final decisions. This calculator limits that risk. It keeps formulas transparent, outputs organized, and engineering checks faster during design reviews and troubleshooting tasks daily.
It solves the missing value among power, torque, and RPM. Enter any two main values and leave one blank. The tool converts units automatically and returns design support metrics too.
The base relation is power equals torque multiplied by angular speed. In this file, RPM is converted to radians per second so the equation works with standard engineering units.
Efficiency helps estimate required input power. Real drives lose energy through heat, friction, and transmission losses. A lower efficiency means the source must deliver more power than the shaft output.
Service factor adds design margin. It is useful when loads are variable, shock driven, or uncertain. The calculator multiplies shaft torque by this factor to estimate design torque.
Yes. The calculator converts all supported units into a common base before solving. That reduces manual conversion errors and lets you compare outputs in several engineering formats.
The equation has three linked variables. If all three are entered, nothing needs solving. If two or more are blank, the system lacks enough data for a valid engineering result.
The chart shows how power changes with RPM while torque stays constant at the solved shaft value. It is a quick visual aid for trend review and machine behavior checks.
Yes. It helps with motor sizing, gearbox checks, coupling review, shaft analysis, and maintenance troubleshooting. It is also useful for teaching the relationship between rotating machine variables.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.