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About STP Calculator

STP Online Calculator

STP Calculator is a web-based tool (with a downloadable option) that simplifies fractional horsepower motor and gearmotor selection for engineers and product designers. Quickly calculates Speed, Torque and Power and accurately converts units of measurement

The STP Online Conversion Calculator provides a fast, easy way to calculate speed, torque or power. The most commonly used units can be selected and conversions are automatically and accurately generated. You enter two of the three variables – speed, torque or power – and STP calculates the remaining value.


STP Downloadable Desktop Calculator

The MOTORTEC™ STP conversion calculator provides a fast, easy way to calculate speed, torque, or power. Conversions of the most commonly used units are selectable, automatically generated and can be printed out.

  • Calculate Speed, Torque and Power
  • Calculate Estimated Electrical Current and Losses for Optimum Motor Selection
  • Easily and Accurately Convert Units of Measurement
  • Customizable, Printed Report Function
  • Calculate Operating Costs.

Windows 7 UsersView installation instructions

Questions? View FAQ’s




STP Reports

STP reports are detailed and comprehensive, as well as customizable.

Speed, Torque and Power Calculations:

Rotational devices such as motors and gearmotors are given specifications in relationship to speed, torque and horsepower. The relationship between these variables follows the equation below.

Power= Speed x Torque / 5252.11…

Where the associated units are:

Speed = RPM

Torque = ft-lb

Power = Horsepower

There are a number of web sites that give additional information on the history of Horsepower and its calculation by searching the key word “horsepower”.

Converting Units:

STPe can also be used simply as a tool to reliably and accurately convert units.

Calculating Electrical Input and Losses

STP has an added feature to calculate estimated input power and losses. Based on the power requirements determined in the STP calculation, additional information can be entered in the Electrical Input and Loss calculator, to estimate electrical values based on the efficiency of the system.

Calculating Annual Operating Cost:

To calculate the annual operating cost, it is first necessary to enter the following operational parameters:

  • Hours/Day
  • Days/Week
  • Weeks/Year

STP uses this data to calculate total Hours/Year operation. The button marked “Get KWh Rate” links to the U.S. Department of Energy website for electrical power rates by location. The selected kWh rate should be entered into the $/kWh data field for final calculation of annual operating cost.


Conversions used in the program are listed below (STP calculations are accurate to nine decimal places)

pi = 3.141…

1 Pound = 16 Ounces

1 Foot = 12 Inches

1 Inch = 2.54 Centimeters

1 Meter = 100 Centimeters

1 rpm = 2 pi / 60 radians

1 Newton = 100,000 Dynes

1 Newton = 0.2248… Pounds Force

1 hp = 745.6998… Watts