What belongs in the cooking-energy calculation?
The price of a dinner is not limited to the ingredients. An electric oven, hob, microwave or air fryer also uses electricity while the food is prepared. If you want a cost per serving that includes cooking, calculate the energy cost for the entire batch first and divide it by the portions actually produced. This is a household budgeting method, not a nutrition calculation: kWh on an electricity bill must never be confused with kcal in food.
The figures below are a worked hypothetical example in euros, not measured electricity use, verified supermarket prices or a current German tariff. Replace them with your own appliance information, time and electricity bill.
Three inputs and the formula
You need three things: electricity use in kilowatt-hours (kWh), the variable price per kWh from your tariff, and the number of servings. The basic equations are:
- Energy (kWh) = input power (W) × active time (hours) ÷ 1,000.
- Batch energy cost = kWh × electricity price per kWh.
- Energy cost per serving = batch energy cost ÷ servings.
For a simple single-rate tariff, use the tax-inclusive unit price. If your electricity price changes by time of day, use the price relevant to cooking time. The standing charge is a separate fixed household cost and is not automatically included in the marginal cost of this meal.
Method 1: estimate from watts and time
Imagine an oven labelled 2,000 W and a cooking session lasting 45 minutes. Convert 45 minutes to 0.75 hours. If the oven drew its full rated 2,000 W throughout, the arithmetic would be 2,000 × 0.75 ÷ 1,000 = 1.50 kWh. At a purely illustrative €0.30/kWh, that would mean €0.45 per batch or €0.1125 per serving for four equal servings.
This is a rated-power scenario, not a measurement or reliable prediction of how much a thermostatically controlled oven actually draws. Use it only as a transparent starting assumption; actual energy can be lower or different. A displayed microwave cooking-output rating is likewise not necessarily its electrical input rating.
Method 2: use measured electricity
Suppose a suitable energy measurement instead shows 0.90 kWh for the same complete cooking session, including any preheating that was measured. Multiply 0.90 × €0.30 = €0.27 per batch. For four servings that is €0.0675, approximately €0.07 per serving if rounding at the end.
A plug-in electricity meter may help for compatible countertop equipment; built-in ovens may require an appropriate circuit-level monitor or reliable energy information from the appliance. Use only meters rated for the appliance and installation. Do not try to access mains wiring to obtain a reading. Record exactly what the measurement includes: preheating, fan, holding temperature and any other stages.
Divide the batch cost between servings
Use the number of meals the batch genuinely supplies. Four equal portions split €0.27 evenly; two portions would put €0.135 of the same batch's electricity into each. The food may be portioned by weight, but cooking energy usually belongs to the whole oven or pan session, not to the grams of one ingredient.
If several dishes cook together, do not charge the entire oven session to each dish. You can apportion a shared measured cost by a documented practical rule, such as the portions cooked, while explaining that the allocation is an accounting convention. Keep the sum of allocated costs equal to the original batch cost. For meals frozen for later, count the first cooking session once and add any separately measured reheating energy when it occurs.
What happens when your tariff changes?
A hypothetical tariff of €0.30/kWh is only a calculation input. With the same observed 0.90 kWh, a tariff of €0.20/kWh gives €0.18 per batch, or €0.045 per serving across four portions; at €0.40/kWh, the numbers become €0.36 per batch and €0.09 per serving.
Do not use national averages in place of your bill without labelling the approximation. Check whether your bill quotes prices inclusive of taxes, whether different peak/off-peak rates apply, and whether the calculation is intended to show marginal cooking electricity rather than a share of fixed household charges.
| Scenario | Batch electricity | Per serving (4) |
|---|---|---|
| 0.20 EUR/kWh · 0.90 kWh | 0.18 EUR | 0.045 EUR |
| 0.30 EUR/kWh · 0.90 kWh | 0.27 EUR | 0.0675 EUR |
| 0.40 EUR/kWh · 0.90 kWh | 0.36 EUR | 0.09 EUR |
Rated power is not actual oven consumption
Power, time and energy are related but different. 2,000 W is a power rating, not 2,000 kWh used. Ovens heat up and switch elements on and off; different temperatures, preheating, batch sizes and cookware change the pattern. A 45-minute cooking time is also not necessarily 45 minutes of full-power draw.
National Energy Action notes that thermostats make some appliances vary their electricity use, so multiplying maximum rated power by clock time does not establish a precise cooking cost. When accuracy matters, prefer a suitable measured kWh value for the actual recipe and appliance. Never compare two appliances using wattage alone without considering time, capacity and the cooking result.
Which extra cooking steps count?
Decide where the energy boundary starts and ends. For oven cooking, note whether the 45 minutes includes preheating. For pasta, you might also heat water and simmer sauce on separate rings. Those are separate energy-consuming steps; add measured or transparently estimated kWh for each, never guess they are zero.
If a dish is reheated the following day, its reheating adds another session. If the oven is used for a second tray at the same time, record one shared session rather than two imaginary full sessions. Gas cooking requires the gas tariff and appropriately measured or estimated gas consumption; the electricity-only examples here cannot be copied straight to a gas hob.
Keep the calculation separate from food costs
Ingredients and cooking energy answer two different budget questions. An illustrative batch with €2.00 in consumed ingredients and €0.27 in measured electricity costs €2.27 in these two categories, or €0.5675 per serving across four servings before rounding. It does not include shopping trips, appliance depreciation, labour, water, packaging or fixed utility charges.
For ingredient portioning, the separate guide on Mealisa explains how to calculate the cost per meal. Do not add the €0.27 a second time if an existing recipe budget already includes the same cooking session. And do not use this monetary cost to infer the meal's nutritional calories.
Related practical guide: calculate ingredient cost per meal.
A reusable five-minute checklist
For any new recipe, jot down the appliance and actual input rating, cooking and preheating times, measured kWh if available, tariff, and final portion count. Keep the raw kWh and batch total before rounding. Update just the electricity unit price when a new contract starts; update the energy-use figure when you change equipment or method.
A useful short record is: oven / 0.90 kWh measured / €0.30 per kWh / €0.27 per batch / 4 servings / €0.0675 per serving. Label the date, recipe and meter boundary. This creates a repeatable estimate without pretending that every oven or every home behaves identically.