Comparing the purchase price of a kitchen appliance is only part of the decision. This guide shows how to estimate electricity use and running costs for ovens, fridge freezers, dishwashers, kettles, coffee machines and countertop cookers, using figures you can update when your tariff, routine or appliance changes.
Overview
The cheapest kitchen appliances to run are not necessarily the ones with the lowest wattage or the best-looking efficiency claim. Running cost depends on four things: the appliance’s energy use, how long it operates, how often you use it and the electricity rate you pay.
That is why a useful comparison should look beyond the number printed on a rating plate. A high-powered kettle may use less electricity overall than a lower-powered appliance that runs for much longer. Similarly, a large fridge freezer may have a relatively modest power draw at any moment but operates continuously, so its annual energy figure is more useful than its wattage alone.
Use the method below when comparing energy efficient kitchen appliances in the UK, checking whether a replacement is worthwhile or reviewing the cost of an appliance you already own. Treat every result as an estimate rather than a promise: cooking habits, room temperature, load size, standby behaviour and maintenance all affect real consumption.
For related buying decisions, see our kitchen appliance running costs comparison, integrated oven buying guide and fridge freezer size guide.
How to estimate kitchen appliance running costs
Start with the appliance’s energy figure. Depending on the product, this may be shown in watts (W), kilowatts (kW), kilowatt-hours per cycle (kWh/cycle) or kilowatt-hours per year (kWh/year). Do not treat these units as interchangeable.
The basic formula
For an appliance with a stated power rating, use:
Energy used per session (kWh) = power in kW × operating time in hours
Then calculate the cost:
Cost per session = energy used in kWh × your electricity rate per kWh
To estimate a monthly or annual figure:
Total cost = cost per session × number of sessions
Convert watts to kilowatts by dividing by 1,000. For example, a 2,000W appliance is rated at 2kW. If it ran continuously for 30 minutes, the simple estimate would be 2kW × 0.5 hours = 1kWh. Heating elements and compressors may cycle on and off, so this is often a maximum-style estimate rather than a precise measurement.
A reusable comparison worksheet
| Appliance | Rated power or label figure | Use per session | Sessions per week | Estimated kWh | Estimated cost |
|---|---|---|---|---|---|
| Oven | Power in kW, or cycle figure if supplied | Preheat plus cooking time | Your normal weekly use | kW × hours × sessions | kWh × tariff |
| Fridge freezer | Annual kWh from product information | Not calculated by session | Use annual figure | Annual kWh ÷ 12 | Monthly kWh × tariff |
| Dishwasher | kWh per cycle where available | One selected programme | Cycles per week | kWh/cycle × cycles | kWh × tariff |
| Kettle | Power in kW | Boiling time and water volume | Boils per week | kW × hours × boils | kWh × tariff |
| Coffee machine | Power in kW | Brewing plus heat-up time | Drinks per week | kW × hours × drinks | kWh × tariff |
| Air fryer or multicooker | Power in kW | Cooking time | Uses per week | kW × hours × uses | kWh × tariff |
Record the tariff you actually pay, including the unit rate relevant to electricity use. If your tariff has time-of-use pricing, calculate separate estimates for each period. Keep the standing charge out of individual appliance comparisons unless you are comparing the total cost of a household energy plan; it generally does not change when one appliance is used.
Inputs and assumptions
A fair comparison uses the same conditions for every appliance. Before filling in the worksheet, write down the following inputs:
- Electricity rate: enter your current price per kWh and the date you recorded it.
- Operating time: use a typical session, not the shortest advertised programme or the longest possible use.
- Frequency: count realistic weekly or daily use. A family kitchen and a one-person household will produce different results.
- Load or quantity: note whether the appliance is full, partly loaded or being used for a single portion.
- Mode: record the programme, temperature and functions you normally select.
- Label basis: check whether the published figure is per cycle, per year, per serving or based on a particular programme.
For ovens, include preheating where you normally do it, but avoid assuming the heating elements draw their full rated power for the entire cooking period. An oven’s wattage is useful for understanding capacity and electrical requirements, while a plug-in energy monitor or repeated readings can provide a better picture of actual use.
For fridge freezers, prefer the annual energy figure supplied with the model over a calculation based on rated wattage. The compressor cycles rather than running constantly, and usage varies with ambient temperature, door opening, ventilation and food load. Correct temperature and adequate airflow matter too; our fridge freezer temperature guide covers those practical checks.
For kettles, fill only the water you need and measure a normal boil. For coffee machines, include warm-up and standby time if the machine remains hot between drinks. For dishwashers and countertop cookers, compare the same quantity of food or washing-up, not simply the same number of minutes.
Energy labels and product sheets can make models easier to compare, but read the accompanying units and test conditions carefully. A label figure is a standardised reference, not a guarantee of your household’s result. Features such as insulation, automatic shut-off, eco modes and batch cooking may matter as much as the headline rating.
Worked examples
The following examples use an illustrative electricity rate of 30p per kWh. It is not a current price recommendation; replace it with your own tariff before making a decision.
Kettle
Suppose a kettle is rated at 3kW and takes six minutes to boil the amount of water normally used. Six minutes is 0.1 hours, so the estimate is 3kW × 0.1 = 0.3kWh per boil. At 30p per kWh, that is 9p per boil. Used 14 times per week, the illustrative cost is £1.26 per week, before allowing for differences in fill level and automatic shut-off.
Air fryer
Assume a 1.5kW air fryer runs for 25 minutes, or 0.417 hours, for one meal. The simple estimate is 1.5 × 0.417 = 0.626kWh, rounded to 0.63kWh. At 30p per kWh, the session costs about 19p. If it is used five times a week, the illustrative weekly cost is about 95p. A shorter cooking time, a fuller basket or a different programme will change the result. Use the same portion size when comparing it with an oven.
Fridge freezer
Imagine a product sheet gives an annual consumption figure of 250kWh. At the illustrative rate, the annual electricity cost would be 250 × £0.30 = £75, or about £6.25 per month. This is a straightforward calculation, but actual cost may differ because the published figure comes from standardised testing rather than your kitchen’s conditions.
Comparing an oven with a countertop cooker
Do not compare a 2kW oven with a 1.5kW air fryer solely by wattage. Estimate the energy used for the same food quantity: include oven preheating and cooking time, then record the air fryer’s heat-up and cooking time. If the oven cooks several portions at once while the air fryer needs two batches, include both air-fryer sessions. Capacity and cooking time can reverse an apparently simple power-based comparison.
When to recalculate
Revisit your worksheet whenever your electricity rate changes, your tariff changes structure or your household routine changes. A move, a new baby, more home cooking, a dietary change or working from home can alter appliance frequency enough to make an old estimate misleading.
Recalculate before replacing a major appliance, especially a fridge freezer, oven or dishwasher. Record the old appliance’s typical use for a week if possible, then compare it with the candidate model using matching loads and programmes. Include purchase price, installation, capacity, warranty and expected lifespan in the wider decision; a small running-cost difference may not justify replacing a serviceable appliance early.
Update the worksheet when manufacturers revise product information, label formats or testing methods. Check the latest label and technical sheet for the exact model rather than relying on a retailer’s shortened description. If you are comparing noise as well as energy use, our guide to quiet kitchen appliances can be used alongside the cost calculation.
For a practical next step, choose three appliances, collect their figures, enter your current tariff and calculate the cost per comparable task. Then check whether the comparison uses the same portion, load and programme. This simple discipline produces a more useful buying guide than a wattage list alone and gives you a worksheet you can refresh whenever prices, products or habits change.
