Electric Motor Calculators

A complete set of free engineering tools for electric motors — from kW/HP conversion, speed, torque and full-load current to energy savings, cable sizing, protection, star-delta starting and VFD scaling. Pick the calculator you need below; each one runs instantly in your browser.

DRG Motor is an İzmir-based wholesale electric motor supplier. We built these calculators so engineers, electricians and buyers can size, compare and verify motors without spreadsheets. The 14 tools below are grouped by what you are trying to do — running the numbers, estimating energy and cost, designing the installation, sizing the mechanical drive, or planning how the motor starts and runs.

Core Motor Calculations

Starting-point tools to quickly find an electric motor's power, speed, torque and current values — or to pick the right motor for an application.

Electric Motor Calculator — kW/HP, RPM, Torque, Current

Convert kW ⇄ HP and compute synchronous speed, full-load torque and three-phase full-load current in one place.

Motor Full-Load Current Chart (kW → A)

Full-load current per kW (400 V / 230 V) reference chart plus a quick current calculator.

Electric Motor Selection Guide | Which Motor?

Get the recommended efficiency class, body and mounting by application, power and speed — and jump to matching products.

Energy, Cost & Environment

Tools that quantify the yearly energy, cost and emission impact of upgrading to a high-efficiency IE3/IE4/IE5 motor.

Electric Motor Energy Savings & Payback Calculator

Calculate annual energy and cost savings plus payback time when moving to a more efficient motor.

Electric Motor Energy Consumption Calculator (kWh & Cost)

Find yearly consumption (kWh) and electricity cost from power, load, efficiency and running hours.

Motor CO₂ Savings Calculator | Carbon Reduction

Estimate the annual CO₂ reduction (environmental impact) of stepping up the efficiency class.

Electrical Installation & Protection

Power-factor correction, cable sizing and protection-device selection for a correctly installed motor circuit.

Power Factor Correction (kVAr) Calculator

Find the capacitor power (kVAr) needed to correct power factor from cos φ₁ to cos φ₂.

Motor Cable Size & Voltage Drop Calculator

Estimate the minimum copper cable cross-section and voltage drop for a three-phase motor circuit.

Motor Overload, Fuse & Contactor Selection

Indicative thermal setting, gG fuse and AC-3 contactor size for a DOL motor from its rated power.

Drive & Mechanical Transmission

Mechanical-side calculations: pump/fan power, gearbox output and pulley-belt transmission.

Pump & Fan Motor Power Calculator

Estimate shaft power and recommended motor rating for pumps (flow+head) and fans (flow+pressure).

Gearbox Output Speed & Torque Calculator

Calculate a geared motor's output speed and torque from the reduction ratio.

Pulley & Belt Drive Calculator (Speed & Diameter)

Pulley diameter-speed relation (n₁·d₁=n₂·d₂), drive ratio and belt speed.

Starting & Variable-Speed Drive

How starting the motor and controlling its speed affect current, torque and power.

Motor Starting Methods: Star-Delta, DOL, Soft, VFD

Compare starting current and torque across DOL, star-delta, soft starter and VFD methods.

VFD Frequency-Torque-Power Calculator

Motor speed, torque and power vs drive frequency; constant-torque and constant-power regions.

From calculation to the right motor

Once you know the power, speed and efficiency class you need, choose the motor itself. Useful catalogue pages:

Electric motors — full range and how to choose
IE3 / high-efficiency motors
Motors by power & speed (kW / rpm)
Selection Guide — answer a few questions, get a recommendation

Related electric motor products

Worked out the power, speed or efficiency class you need? Browse the matching DRG Motor product families and request a quote.

IE3 Electric Motors IE4 Electric Motors IE5 Electric Motors High-Efficiency Motors Three-Phase Asynchronous Motors Single-Phase Asynchronous Motors General Purpose Industrial Motor Stone Crushing Plant Motors Fan Motors Pump Motors Vibration Motors

See all electric motors →

Frequently asked questions

Are these calculators free?

Yes. All 14 electric-motor calculators on this page are free to use, run entirely in your browser and require no sign-up.

Which calculator should I start with?

For a general motor check use the Electric Motor Calculator (kW/HP, RPM, torque, current). If you are choosing a motor for a job, start with the Selection Guide.

Can I size cables and protection here too?

Yes — use the cable size and thermal, fuse & contactor tools for the installation side.

Are the results suitable for final engineering design?

They give reliable indicative values based on standard three-phase formulas. For final design always confirm against the motor nameplate, manufacturer data and local electrical regulations.

Where can I find the motors themselves?

Browse our electric motors catalogue, or use the Selection Guide to jump straight to matching products and request a quote.