The short answer
Compare the energy needed for the same total meal, including all batches and preheating. Multiply each method’s whole-meal kWh by your tariff. A smaller appliance is not automatically cheaper when several batches are needed; a complete-meal measurement can capture cycling that rated watts miss.
Compare the whole meal, not one basket against one oven
An air fryer can be economical for a small amount of food, while an oven’s capacity can help when cooking larger quantities together. Energy Saving Trust’s cooking guidance makes portion size and batch cooking part of the choice.
For your own comparison, define the same total portion cooked to the same result. If that portion needs two air-fryer batches and one oven batch, enter those different batch counts.
Include preheating separately
For a constant-input estimate:
Meal kWh = input kW × (cooking minutes per batch × batches + minutes per preheat × preheat sessions) ÷ 60.
Use one preheat session when sequential batches share a preheated appliance. Use a separate session for each fresh warm-up you actually need. Enter zero preheat minutes if the routine requires none.
The cooking comparison calculator lets each method have independent power, cooking time, batch count and preheating inputs.
An illustrative single-meal comparison
These inputs are illustrative constant-power examples, not measured products, recipe instructions or averages.
| Input or result | Air fryer | Electric oven |
|---|---|---|
| Electrical input | 1,500 W | 2,200 W |
| Cooking time per batch | 20 minutes | 40 minutes |
| Batches for the whole meal | 1 | 1 |
| Preheat | 3 minutes, once | 10 minutes, once |
| Calculated energy | 0.575 kWh | About 1.833333 kWh |
| Cost at £0.28/kWh | £0.16 | £0.51 |
Using unrounded energy, the difference is about £0.352333 per meal. At four comparable meals per week and 52 weeks, the illustrative annual difference is £73.29.
If the air fryer needs two 20-minute batches sharing one three-minute preheat, its energy becomes 1.075 kWh. Its meal cost is about £0.30, and the same annual comparison falls to £44.17. The quantity of food must still be comparable.
Measured meal energy includes everything already captured
Cooking appliances can change their input while maintaining a temperature. Rated power for every minute can therefore differ from the energy used by the completed meal.
In measured mode, enter kWh for the whole comparable meal, including all preheating and batches. The tool uses that energy directly. It does not multiply it again by the number of baskets or add preheating a second time.
Each option can use its own basis, but a measurement for one exact routine and a constant-power estimate for another have different uncertainty. Repeat a suitable measurement if the recipe, portion or appliance setting changes.
Keep annual savings in perspective
The annual result holds the entered meal frequency and tariff constant for 52 weeks. It covers electricity for the two methods you entered, excluding purchase price and other meal preparation.
An energy saving alone does not establish whether buying a new appliance pays back. Use the purchase-comparison guide for that separate decision. Read microwave input and output watts before estimating a reheating alternative.