Calculator Directory

All Engineering Calculators

Every kW Calc tool in one place. Search by name or unit, filter by category, or jump straight to the field you work in.

Calculators
505
Categories
13
Design tools
6
Price
Free

Showing all 505 calculators

Advance Design Tools

Multi-step design tools that take you from load study to a complete component list.

6 toolsCategory page

Power System Calculators

Convert and size kW, kVA, kVAR, amps, volts and ohms, and work with impedance, reactance, capacitance and inductance.

104 calculatorsCategory page

Most used

All Power System calculators A–Z

Pump Calculators

Size water, well, pool, submersible and heat pumps, and convert flow, head, pressure and pump power.

108 calculatorsCategory page

Most used

All Pumps calculators A–Z

Battery Calculators

Work out battery capacity, runtime, charging time and bank size, and convert Ah, Wh, mAh and CCA.

45 calculatorsCategory page

Most used

All Battery calculators A–Z

Generator Calculators

Size standby and home generators, and estimate current, fuel use, runtime, breakers and exhaust.

53 calculatorsCategory page

Most used

All Generator calculators A–Z

Motor Calculators

Find motor full load amps, power, torque, speed and starting current, plus cable, breaker and overload sizing.

47 calculatorsCategory page

Most used

All Motor calculators A–Z

Cable and Wire Calculators

Size cables, check voltage drop and convert AWG, SWG, kcmil and mm² wire gauges.

30 calculatorsCategory page

Most used

All Cable & Wires calculators A–Z

HVAC Calculators

Calculate BTU loads, AC tonnage, CFM airflow and AHU capacity for heating and cooling.

25 calculatorsCategory page

Most used

All HVAC calculators A–Z

UK Electrical Calculators (BS 7671)

BS 7671 cable sizing, voltage drop, Zs and RCD checks, plus Economy 7 and UK energy costs.

23 calculatorsCategory page

Most used

All UK (BS 7671) calculators A–Z

Solar Calculators

Size solar panels, arrays, inverters, strings and charge controllers, and estimate output and payback.

22 calculatorsCategory page

Most used

All Solar calculators A–Z

Electric Vehicle Calculators

Estimate EV charging time, charging cost, driving range and running cost against petrol and diesel.

10 calculatorsCategory page

Most used

All Electric Vehicles calculators A–Z

Transformer Calculators

Calculate transformer full load and short circuit current, voltage drop, turns ratio and fuse size.

12 calculatorsCategory page

Most used

All Transformer calculators A–Z

Panel Design Calculators

Size busbars, breakers, fuses, contactors, VFDs and star-delta starter components.

10 calculatorsCategory page

Most used

All Panel Design calculators A–Z

Power Factor Calculators

Correct power factor, size capacitor banks and estimate power factor penalties.

10 calculatorsCategory page

Most used

All Power Factor calculators A–Z

Why kW Calc

Built by Engineers, Checked Before Publishing

Every tool in this directory follows the same process, so you can rely on the result.

  • Formulas From the Standards

    Every calculator uses the formula from the governing standard, such as IEEE, IEC, NEC, BS 7671, ASHRAE or NFPA.

  • Reviewed by an Engineer

    Each tool is checked by Nadeem Sial, a Senior Electrical Engineer with 15+ years of field experience.

  • Free, No Sign-Up

    All 500+ calculators are free to use. There is no account, subscription or download.

  • Works on Any Device

    Pages are fast and fully responsive, so you can calculate on site from a phone or tablet.

How We Develop Each Calculator

  1. 1

    Research and Formula Sourcing

    We start with authoritative references such as IEEE standards, ASHRAE handbooks, NFPA codes and peer-reviewed engineering data to identify the correct formula for each calculation.

  2. 2

    Formula Validation

    Each formula is cross-checked against real-world engineering scenarios and validated by our Senior Electrical Engineer with 15+ years of hands-on industry experience.

  3. 3

    Build and Test

    The calculator is built with clean logic, edge-case handling and unit-aware inputs. We run sample calculations side by side with industry tools to verify accuracy before publishing.

  4. 4

    Expert Review and Publish

    A final review checks the result range, input labels, unit consistency and explanatory text. Only then is the tool published and linked into the kW Calc library.

FAQ

Frequently Asked Questions

What is kW Calc?

kW Calc is a free online library of 500+ engineering calculators. It covers power systems, motors, generators, transformers, cables, panel design, power factor, solar, batteries, electric vehicles, HVAC, pumps and UK BS 7671 calculations.

Are these calculators accurate?

Yes. Every calculator is built on the formulas published in industry standards and engineering handbooks. Each one is reviewed by Nadeem Sial, a Senior Electrical Engineer with 15+ years of experience.

Do I need to sign up to use kW Calc?

No. All tools are 100% free to use with no account, subscription or login. Open a calculator and start calculating.

How do I find the right calculator?

Type a unit or task in the search box at the top of this page, such as "kVA to amps" or "pump head", or use the category filters to show one group at a time. Each category also has its own page with a step-by-step sizing guide.

Can I use kW Calc on mobile?

Yes. kW Calc is fully responsive and works on smartphones, tablets, laptops and desktops.