Power Requirement Calculator | kVA / KW Calculator

How much power do you need?

Before deciding on a generator, it is important to consider ALL the appliance you may want to operate, how many will be used simultaneously and the TOTAL current consumption at any one time. Most appliances have a descriptive plate stating the current, usually in watts.


Various electrical applications have very different power requirements, so it is essential to understand each particular need. For example TV sets, cookers, kettles and filament lamps have resistive loads, this means that their start up and operating currents are virtually the same - and as stated on the manufactured descriptive plate. Buying the right generator can seem like a formidable task. But in just a few easy steps you can effectively and confidently decided and choose which generator is right for you.

  1. Identify the tools and appliances you wish to operate with your generator.

  2. Determine the required power for each item ( see appliance data plate i.e.: watts of appliance).

  3. Add the required Watts of each item that will be running simultaneously. Also allow for motor starting of appliance (see below)

  4. Choose the generator that has rated watts that meet or exceed this total power.

Motor starting is an important consideration when buying a generator. Keep in mind that induction type motors, like those that run sump pumps, refrigerators, compressors, pressure washers typically require 2 to 3.5 times their listed running watts to start. below is a chart you can use to determine how many Watts you will need to start up motors of various sizes and types. Please note that power tools using a universal commutator do not require any additional start up power. The calculator below lists tools and appliances you may want to use with your generator. With each tool or appliance is listed the approximate running watts for each. 

Note: Always consult the data plate on the tool or appliance for accurate electrical information. The outlet configuration of some units may require modification to achieve maximum rated power. If you are in any doubt then consult the manufacturer of your appliance, simply ask them this, "I have your model #????? I wish to run this via a generator. What is the start up wattage or the kVA of the generator I need?"

Disclaimer: Because of the tremendous amount of variables that exist in generator power provision and transmission, Absolute Generators strongly suggests that you seek the advisement of a certified electrical professional familiar with your situation (and potentially local electric code when performing permanent installations). Information offered by this generator power calculation page, though a useful tool for general estimating, requires consideration of circumstances specific to your application including, but not limited to: electric motor efficiencies (or lack-there-of), altitude, derating of generator power based upon fuel type, prime power versus standby power concerns, simultaneous versus varied timing of loads, site conditions, iron losses, etc... Please contact us at +44 (0) 1630672761 Mobiles & Whatapp +44(0)7483838474 / Email enquiries@primepowersolution.com with your specific situational needs and concerns. Complex electrical calculations beyond that which is represented by the above page requires consultation with onsite certified electrical professionals. Because of the unlimited variables that exist in generator power situations, Absolute Generators accepts no liability associated with your use of this page and the information it provides.