How to Calculate Amps, Volts and Watts

How to Calculate Amps, Volts and Watts

Operators of commercial kitchens make large investments in appliances and equipment. From this investment, they want to see top performance and get the longest life possible out of these products. An important aspect of achieving the desirable performance, longevity and safety of foodservice equipment is ensuring the proper power supply.

“Commercial kitchens use about 2.5 times more energy per square meter than other commercial spaces," says Natural Resouces Canada in their ENERGY STAR Guide for Commercial Kitchens. "Commercial kitchen equipment can be operated for hours at a time and is often very energy-intensive."

Selecting a piece of foodservice equipment that isn’t compatible can pose a safety hazard. If you are unsure, consult a licensed electrician before adding, changing, or ordering new equipment. Be prepared if adding larger appliances and equipment that the electrical system may need an upgrade. If you have a product that requires more power than is available, you will have an underperforming product or cause overloads. Having more juice flowing to the appliance than is required can risk damaging and shortening the life span of the equipment.

What you should know about your power supply

1. Know the power supply of your building in amps – you should be able to find this information on your main breaker or marked on the nameplate sticker on the side of your meter base.

2. Know the voltage of your equipment and appliances products – this information can be found on rating plate on the equipment and in the product manual.

3. Know the watts and/or amps of all of your equipment and appliances - this information can be found on the rating plate on the equipment and in the product manual.

For each piece of equipment, if you know at least two of either amps, volts or watts you can calculate for the the third to get the full picture on the electricity needs of your appliances.

Conversion Calculator for Amps, Volts and Watts

Volts = Watts ÷ Amps

Watts = Amps x Volts

Amps = Watts ÷ Volts

Calculation example:

A 240 volt product that takes 480 watts of power will draw 2 amps (480 ÷ 240 = 2).

Why you should know the amps, volts and watts for each piece of equipment in your commercial kitchen (and dining room)?

Volts and amps provide the information you need to size wires, fuses and circuit breakers and watts tell you the rate of power that will be generated or consumed by a product.

Volts: Voltage measures the force or pressure of the flow of electricity.

Amps: Amperes measures the rate the electricity is flowing.

Together, volts and amps give insight into the amount of current drawn by an appliance or circuit.

Watts: Wattage is the measurement of the electrical power flow.

Watts can be viewed as a measure of the power of an appliance or the amount of power it needs to work.   While volts and amps are the potential for power.

Your electricity bill reflects how many kilowatt hours (kWh) your business has used - the amount of kilowatts (1000 watts) used per hour.

With the rate shown on your electricity bill, you can calculate how much each of your appliances costs to operate daily.  Multiply the equipment's wattage by the number of hours used in a day.  Divide by 1000.  Multiply by your kWh rate.

Example: 4 Slot Heavy Duty Toaster

kWh rate: $0.15
Toaster Wattage: 2700 W
Hours used daily: 3

2700 W x 3 h/day = 8100 Wh/day

8100 Wh/day ÷ 1000 = 8.1 kWh/day

8.1 kWh x $0.15/kWh = $1.22 / day


Once operators find the building’s potential power supply or the total amps, it’s important to understand that you only want to use 80 percent of that capacity. A 20 percent buffer is left for safety. Why?  This allows a buffer for when high draw items are added that push it over the 80 percent for small bursts of time when first turned on.

For example, if your facility has a 100 amp electrical system, and your operation is currently using 77 amps of service you shouldn't add a piece of equipment that will draw more than 3 amps of service.

Commercial kitchens use a large portion of their electrical load on refrigeration, freezers, fryers, ovens and icemakers. Operations can save money by choosing equipment that pairs well with their existing system.

However, using a higher voltage to reduce the current can make electrical systems more efficient.

A product that requires 240 volts will draw fewer amps to provide 480 watts of power than a product that requires 120 volts.  

480 W ÷ 240V = 2 amps

480 W ÷ 120V = 4 amps

Large commercial kitchen equipment often does not come with a plug-in feature and therefore needs to be hard wired in. If you are bringing in an electrician to wire in the equipment, it may be prudent to consult before ordering the equipment.

This proactive step can save time, money and a few headaches. A professional can guarantee you’re purchasing equipment that your system can handle, and avoid having to send back equipment or possibly having to upgrade the buildings service panel.

A basic understanding of the amps, volts and watts used in your restaurant, cafe, bakery or pub will ensure the safety, longevity and efficiency of their valuable appliances and equipment.

Written by Breanne Baker

Tangle of power cords