Free calculator
Equipment running cost calculator
What does that fryer, chiller or air conditioning unit actually cost you a year? Enter its power rating and the hours it runs to find out, and see what switching it off an hour earlier would save.
Cost = watts ÷ 1,000 × hours × duty cycle × unit rate. The default unit rate is the Q2 2026 average all-in price for the smallest business electricity users (38.36p per kWh, DESNZ), so replace it with your own rate for an accurate figure. Preset wattages are starting points, not measurements: always use the rating plate.
How to work out running costs
Power in kilowatts × hours run × unit rate = cost. The only complication is that most equipment does not draw its full rated power the whole time it is switched on.
A worked example, with the inputs shown: a 2,000W heater, on for 10 hours a day, 6 days a week, drawing full power, at 30p per kWh. That is 2kW × 10 hours = 20 kWh a day, 120 kWh a week, and about 6,240 kWh a year. At 30p, roughly £1,872 a year before VAT, from one heater.
Finding the power rating
Look for the rating plate: a label on the back, base or inside the door, or the first page of the manual. It shows watts (W) or kilowatts (kW). If it only shows amps, multiply amps by 230 for a rough single-phase wattage, or by 400 and then by 1.73 for three-phase. Our guide to single-phase and three-phase supplies explains the difference.
A plug-in energy monitor is better still for anything that cycles, because it measures what the equipment actually draws rather than what it could draw.
Why duty cycle matters
A commercial fridge is switched on 24 hours a day, but its compressor only runs when the thermostat calls for cooling, perhaps a third of the time. Entering 24 hours at 100% would overstate its cost threefold.
| Type of equipment | How to enter it |
|---|---|
| Lighting, PCs, screens, servers | Hours switched on, duty cycle 100% |
| Fridges, freezers, cold rooms | 24 hours, duty cycle around a third, adjusted for how warm the room is |
| Heating and air conditioning | Hours the system is enabled, duty cycle by season |
| Ovens, fryers, kettles, hand dryers | Hours actually in use, duty cycle 100% |
| Motors and compressors | Hours running under load, duty cycle by process |
What to do with the answer
- Find the expensive items. Run the numbers for your five biggest pieces of equipment. Most businesses find one or two items account for a surprising share of the bill.
- Test a change before you make it. Halve the hours, or drop the wattage to an LED equivalent, and see the difference in the yearly figure.
- Justify a replacement. Divide the price of new equipment by the annual saving to get a simple payback in years.
- Check the rate underneath. Running costs scale directly with your unit rate, so a cheaper contract cuts every one of these figures at once.
Our guides to reducing business energy costs, LED lighting and energy audits go further, and the cost calculator turns your whole bill into an all-in price you can compare.
Running cost questions
How do I work out what a piece of equipment costs to run?
Multiply its power rating in kilowatts by the hours it runs, then by your unit rate in pence per kWh. A 2kW heater running 8 hours a day at 30p per kWh costs 2 × 8 × 30 = 480p, or £4.80 a day.
Where do I find the wattage of my equipment?
On the rating plate, usually a metal or printed label on the back or underneath, or in the manual. It will show watts (W) or kilowatts (kW). If it shows amps, multiply amps by 230 for a rough wattage on a single-phase supply.
Does equipment use its full rated power all the time?
Rarely. Fridges, freezers, air conditioning and heating cycle on and off with a thermostat, so actual use is often between a third and two thirds of the rating. Motors and kettles draw close to full power while running. For cycling equipment, enter the hours it actually runs rather than the hours it is switched on.
What is a duty cycle?
The share of time equipment actually draws power. A fridge switched on 24 hours a day might only run its compressor for 8 of them, a duty cycle of about a third. This calculator has a duty cycle field so you can allow for it.
Should I use my unit rate or my all-in price?
Use your unit rate for the cost of running one item, because the standing charge is paid whether the equipment runs or not. Use your all-in price when you are comparing your whole bill with the market.
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