Comparing kitchen appliance running costs is less about finding one universal winner and more about matching the appliance to the meal. This guide shows how to estimate the cost of ovens, air fryers, hobs, microwaves, slow cookers and multicookers using your own wattages, cooking times and electricity tariff, so you can make a more useful appliance comparison and revisit it when those inputs change.
Overview
The cheapest kitchen appliance to run is usually the one that completes the job with the least energy, rather than the one with the lowest wattage printed on its label. A 2,000-watt appliance used for a short period can use less electricity than a 200-watt appliance left on for several hours. Cooking volume, preheating, heat loss and whether the appliance is full also matter.
For example, an air fryer may be a practical choice for a small portion because its compact cooking chamber can heat quickly. An oven may be more sensible for several portions, multiple trays or a large dish. A microwave is often efficient for reheating and cooking suitable foods, while a slow cooker uses modest power over a long period. These are useful patterns, not guarantees: check the instructions, programme length and actual appliance rating for the model you own.
Running cost should also be considered alongside cooking results. An appliance that costs slightly more to operate may save preparation time, cook a larger batch or produce the texture you want. When reading kitchen appliance reviews, look for capacity, warm-up time, automatic programmes, insulation, standby behaviour and whether the appliance maintains its rated power throughout the cycle.
| Appliance | Typical rated power range | Illustrative cooking time | Example energy use at full rated power | Useful for |
|---|---|---|---|---|
| Electric oven | Approximately 2,000–3,500W | 30–60 minutes, plus preheating where required | 1.00–3.50kWh | Large portions, baking, roasting and several dishes |
| Air fryer | Approximately 1,000–2,000W | 15–35 minutes | 0.25–1.17kWh | Small portions, crisp foods and quick meals |
| Microwave | Approximately 700–1,400W input power | 3–15 minutes | 0.04–0.35kWh | Reheating, defrosting and microwave-suitable cooking |
| Induction or ceramic hob | Approximately 1,200–3,000W per zone | 10–40 minutes | 0.20–2.00kWh | Sauces, boiling, frying and pan cooking |
| Slow cooker | Approximately 100–300W | 4–10 hours | 0.40–3.00kWh | Stews, soups and planned batch cooking |
| Multicooker | Approximately 700–1,500W | 20–90 minutes, excluding natural release | 0.23–2.25kWh | Pressure cooking, rice, stews and one-pot meals |
The figures in the table are broad planning ranges, not model test results. Actual consumption may be lower because thermostats cycle heating elements on and off, and cooking times vary by food, load and programme.
How to estimate running cost
Use this basic formula:
Energy used in kWh = appliance power in watts ÷ 1,000 × time in hours
Then calculate:
Electricity cost = energy used in kWh × your tariff in pounds per kWh
To use the formula, find the appliance's input or rated power on its rating plate, manual or product page. Convert minutes into hours: 30 minutes is 0.5 hours, and 15 minutes is 0.25 hours. If a programme uses different stages, calculate each stage separately and add the results.
For a more realistic estimate, multiply by an adjustment factor when the appliance is unlikely to draw its full rated power continuously. You can leave this factor out for a simple upper-bound estimate, or use your own measured reading from a plug-in energy monitor where the appliance is safe to connect to one. Do not connect high-load appliances such as ovens or hobs to a domestic plug-in monitor unless the equipment is specifically designed and rated for that purpose.
For appliances with a published energy-use figure per cycle, use that figure in preference to a simple wattage calculation. It may account for heating cycles more accurately than multiplying the maximum power by the entire programme duration.
A reusable worksheet
- Appliance: ____________________
- Rated input: ____________________ W
- Cooking time: ____________________ minutes
- Time in hours: ____________________ ÷ 60 = ____________________
- Estimated energy: watts ÷ 1,000 × hours = ____________________ kWh
- Your electricity tariff: £____________________ per kWh
- Estimated cost: kWh × tariff = £____________________
- Meal size and result: ____________________
Repeat the worksheet for the same meal in two appliances. This gives a more meaningful air fryer versus oven running-cost comparison than comparing their wattages in isolation.
Inputs and assumptions
Tariff: Enter the unit rate shown on your electricity bill or account, expressed in pounds per kWh. Do not confuse the unit rate with standing charges; standing charges apply to having a supply and are not normally useful for comparing one cooking session with another.
Rated power: A label showing 2,000W describes the appliance's maximum or nominal input, not necessarily what it draws every second. Ovens, slow cookers and some multicookers cycle their heaters. Motors, fans and control electronics may use additional power, although their contribution can be relatively small compared with heating.
Preheating and preparation: Include oven preheating if you normally preheat for that recipe. Include pressure build-up or release only where the appliance is consuming meaningful power during that period. For an air fryer, include any preheat setting you actually use.
Capacity: Divide the cost by the number of portions only if the entire batch represents the portions you would otherwise cook. Overfilling an air fryer or slow cooker can extend cooking time and affect results, while running a large oven for one small item may reduce its cost advantage.
Food and safety: A lower estimated cost is not a reason to shorten a safe cooking time. Follow the manufacturer's instructions and reliable food-safety guidance, particularly for poultry, meat, reheating and pressure cooking.
For a broader appliance review, assess the complete task: usable capacity, cleaning, noise, controls, repairability information, installation requirements and the quality of the result. Our air fryer versus oven comparison can help with the practical differences, while an integrated oven buying guide is useful when installation and kitchen fit are part of the decision.
Worked examples
Air fryer
Assume a 1,500W air fryer runs for 25 minutes and your tariff is an illustrative £0.30 per kWh. Energy use is 1.5 × 25 ÷ 60, which equals 0.625kWh. The estimated cost is 0.625 × £0.30, or £0.1875, rounded to about 19p. This is an illustration, not a current tariff or a promise that every air fryer will use that amount.
Electric oven
Assume a 2,500W oven is used for 45 minutes, including the period you want to count, at the same illustrative tariff. Energy use is 2.5 × 45 ÷ 60, or 1.875kWh. The estimated cost is 1.875 × £0.30, or about 56p. If the oven cycles its elements and does not draw 2,500W continuously, measured use may be lower. If preheating is additional, add that period to the calculation.
Slow cooker
Assume a 200W slow cooker runs for 7 hours. Energy use at the rated power is 0.2 × 7, or 1.4kWh. At £0.30 per kWh, the simple estimate is 42p. Compare that with the portions produced: a slow cooker may be useful for a large batch even though its programme lasts much longer than an air-fryer cycle.
Microwave
Assume a microwave with 1,000W input power runs for 8 minutes. Energy use is 1.0 × 8 ÷ 60, or 0.133kWh. At the illustrative tariff, that is about 4p. Microwave output power and input power are not always the same, so use the input figure for an electricity estimate when it is available.
These examples show why both time and power matter. They also show why cost per meal or portion is more useful than cost per hour when comparing appliances with different capacities.
When to recalculate
Recalculate whenever your electricity unit rate changes, you replace an appliance or your regular cooking routine changes. A new air fryer with a different basket size, a larger oven, a multicooker with a pressure programme or a slow cooker with a different setting may alter the estimate even if the recipe stays the same.
It is also worth checking after changing portion sizes. Compare the cost of one small meal, a full batch and reheating leftovers rather than assuming the cheapest appliance for one portion is cheapest for every use. If your estimate matters, take a few readings with a suitable energy monitor or use the appliance's own energy information, then average similar cooking sessions.
Keep this worksheet with your appliance manuals and update the tariff, wattage, programme time and portion count. For more ideas on choosing and organising countertop appliances, see our guides to building a small kitchen appliance setup and multicookers and slow cookers. The practical conclusion is simple: measure the meal you actually cook, use the same tariff for each comparison and judge running cost alongside capacity, results and convenience.
