Methodology and Sources for Energy Consumption Estimates

1. General Methodology

All energy consumption values in this tool are measured in watt-hours (Wh), which is the amount of energy consumed over time. The basic formula for calculating energy consumption is:

Energy (Wh) = Power (Watts) × Time (Hours)

For example, a 100-watt light bulb used for 2 hours would consume 200 watt-hours of energy.

Most products on this list are electrical, but energy use for non-electric products (such as petrol car or gas heating) are converted into watt-hour equivalents.

Energy costs are available for a small selection of countries based on their national energy prices (electricity, gas and petrol). This price data is sourced from Eurostat, Ofgem, and the US EIA (based on prices for 2025 or early 2026, depending on availability). Costs reflect average household prices, and don’t reflect dynamic, off-peak or smart tariffs.

Below, I list the assumptions and sources for each product or activity. Again, the actual level of energy consumption will depend on factors such as the specific efficiency of the product, user settings, and climate so these should be interpreted as approximations to give a sense of magnitude.

2. Lighting

Incandescent lightbulb

Traditional incandescent bulbs typically range from 25 to 100 watts, with 60 watts being relatively standard for a household bulb. One hour of use would consume 60 Watt-hours (Wh).

LED lightbulb

LED bulbs use around 80% less energy than incandescent bulbs for the same amount of light output. A standard LED bulb has an energy rating of around 10 W. Using it for one hour would consume 10 Wh.

3. Digital Technologies

Charging a mobile phone

Modern smartphones have battery capacities of 3,000-5,000 mAh at approximately 3.7-4.2V, resulting in batteries around 15-20 watt-hours. If we assume there is around 10% to 20% loss due to charging efficiencies, a full charge likely requires around 20 Wh.

Watching TV – Medium, efficient

Medium-efficiency TVs (for example, 40-50 inch LED TVs) consume approximately 60 watts during active viewing.

Watching TV – Large, modern

Larger modern TVs (55-60 inches with 4K capability) typically consume 80-100 watts. I’ve gone with 90 watts as a reasonable average.

MacBook laptop

The power consumption of Apple MacBooks vary depending on the model and what applications users are running.

When doing everyday tasks such as writing emails, word documents, or browsing the internet, they consume around 5 to 15 watts. Streaming video is more like 15 to 20 watts. When doing intensive tasks such as editing photos or video, or gaming a MacBook Pro can reach 80 to 100 watts.

Here I have assumed an average of 20 watts.

Desktop computer

Desktop computers vary widely, but more efficient models consume approximately 50 watts. When doing light tasks, this can be a bit lower. Gaming computers can use far more, especially during peak usage (often several hundred watts).

Gaming console (Xbox)

The power consumption of game consoles can vary a lot, depending on the model. The Xbox Series S typically consumes around 70 watts during active gameplay. The Xbox Series X consumes around twice as much: 150 watts.

Game consoles use much less when streaming TV or film, or when in menu mode.

Streaming Netflix (streaming only)

The marginal increase in energy consumption for one hour of streaming is around 0.2 Wh. This comprises of just 0.028 Wh from Netflix’s servers themselves, and another 0.18 Wh from transmission and distribution.

To stream video, you need an internet connection, hence a bar for the electricity consumption for Home WiFi is also shown. Note that, for most people, this isn’t actually the marginal increase in energy use for streaming. Most people have their internet running 24/7 regardless; the increase in energy use for streaming is very small by comparison. However, it is shown for completeness.

This does not include the electricity usage of the device (the laptop or TV itself). To get the total for that hour of viewing, combine it with the power usage of whatever device you’re watching it on.

h/t to Chris Preist (University of Bristol) for guidance on this.

Streaming YouTube (streaming only)

YouTube figures are likely similar to Netflix (see above), although they may be slightly higher due to typical streaming patterns and ad delivery. Again, you need to add the power consumption of the device you’re watching on, separately.

Home internet (WiFi)

WiFi routers typically consume between 10 and 20 watts continuously. Here I’ve assumed 15 watts as a reasonable average.

ChatGPT (median query)

Recent research estimates that the median ChatGPT query using GPT-4o consumes approximately 0.3 watt-hours of electricity.

Actual electricity consumption varies a lot depending on the length of query and response. More detailed queries — such as Deep Research — will consume more (but there is insufficient public data to confirm how much).

If improved data becomes available on more complex queries, image generation and video, I would like to add them.

Reading on a Kindle

E-readers like the Kindle use e-ink displays that consume power primarily when refreshing the page. A typical Kindle device has a battery of around 1000–1700 mAh at ~3.7 V, which is 3.7 to 6 Wh. People report it lasting weeks on a full charge with moderate (30 minute per day) reading frequency.

That works out to less than 1 Wh per hour. Here I’ve been conservative and have rounded it up to 1 Wh.

4. Kitchen Appliances

Boiling a kettle

Electric kettles typically have power rating between 1500 and 2000 watts. Boiling a full kettle (1.5-1.7 litres) takes around 3 to 4 minutes.

A 2000-watt kettle that takes 3 minutes to boil will consume around 100 watt-hours.

Microwave

Microwaves typically have a power rating between 800 and 1,200 watts. If we assume 1000 watts, five minutes of use would consume 83 Wh (1000 * 0.08).

Electric oven

Electric ovens can have a power rating ranging from 2,000 to 5,000 watts. A typical one is around 2500 watts.

Once an oven is on and has reached the desired temperature, it typically cycles and runs at around 50% to 60% capacity. I’ve therefore calculated energy consumption as [2,500W × time × 0.55].

Gas oven

Gas ovens consume natural gas for heating but also use electricity for ignition and controls (approximately 300-400 watts). When converting the thermal energy from gas combustion to electrical equivalents for comparison purposes, gas ovens typically use slightly more total energy than electric ovens due to combustion inefficiency.

Similar to electric ovens, I have assumed that gas ovens cycle on and off once they’ve reached the desired temperature.

Air fryer

Small air fryers typically operate at 800W to 1500W. Larger models (especially with two trays) can be as much as 2500W. I’ve assumed 1500 watts in these calculations. Once an air fryer is on, it typically cycles and only runs at around 50% to 60% of capacity. Averaged over a cycle, 1000W is likely more realistic.

Ten minutes of use would consume 167 Wh (1000W * 0.17 hours = 167 Wh).

Electric induction hob (one ring)

Induction hobs are efficient, and tend to have a power rating of 1,000W to 2,000W per ring. I’ve assumed 1,500 watts in these calculations. Like air fryers, they’re often not operating at maximum power draw for the full cooking session. 50% is more typical. That means the average power usage is closer to 750W.

Most cooking activities take less time; typically 5 to 10 minutes, which reduces electricity consumption.

Gas hob (one ring)

Gas hobs convert natural gas to heat. They tend to consume 2 to 2.5-times as much energy as induction hobs to achieve the same heat output. This is because they typically operate at around 40% efficiency, compared to 85% for an electric hob.

If an induction hob has an average rating of 750W over a cooking cycle, the useful heat delivered is 638W (750W * 85% efficiency). To get that useful heat from a gas hob with 40% efficiency would need 1595W (638W / 0.4). Here I’ve assumed an equivalent power input of 1600W.

Small fridge

A small-to-medium refrigerator (around 130 litres) typically consumes around 100 kWh per year, which equals approximately 275 Wh per day on average.

Fridge-freezer

Standard refrigerator-freezer combinations consume anywhere between 200 and 500 kWh per year. Some very efficient models can achieve less than 200 kWh. Here, I have assumed one consumes 300 kWh per year. That is approximately 822 Wh per day.

5. Washing and Drying

Vacuum cleaner (hoover)

Vacuum cleaners typically use 500W to over 1,500W. Popular models in the UK use around 620W or 750W. Here, I have assumed a power rating of 750W. Ten minutes of usage would consume 125 Wh.

Washing machine

Washing machine energy usage varies a lot depending on load size, cycle type and water temperature. An average load in an efficient, modern machine might use 600 Wh to 1,000 Wh per cycle. A large load could be use than 1,500 Wh. Here I have assumed 800 Wh, which is typical for a medium load.

Tumble dryer

Electric tumble dryers are among the highest energy consumers in the home. Heat pump models are much more efficient than condenser or vented models. A condenser or vented model might consume between 4000 and 5000 Wh per cycle. A heat pump model, around half as much.

Here, I have assumed 4500 Wh for condenser or vented cycles, and 2000 Wh for a heat pump cycle. Actual energy consumption will depend on factors such as load size and user settings.

Dishwasher

Most energy in a dishwasher is used for heating the water. They typically use between 1,000 and 1,500 Wh per cycle. Very efficient models can use closer to 500 Wh per cycle. Operating on eco modes will also consume less than 1,000 Wh.

Here, I have assumed 1,250 Wh per cycle, which is fairly average for most users.

Clothes iron

Clothes irons typically have an energy rating between 1500W and 3000W. Steam irons are towards the higher end of the range. Here, I have assumed 2500W, which is fairly standard for a steam iron.

Using one for 10 minutes would consume 417 Wh of power.

Dehumidifier

Dehumidifiers can range from as small as a few 100 watts, up to several thousand for large whole-house units.

Here I’ve assumed a medium, portable one with an energy rating of 500W. And a large unit of 1000W.

In humid conditions, or if they’re being used to dry clothes, they will be running at or close to maximum power draw for a long period of time. In fairly low-humidity conditions, they might cycle on and off after a few hours, meaning their energy use drops to 50% to 70% of the maximum.

6. Heating and Cooling

Hairdryer

Hairdryers typically range from 1,000 to 2,000 watts. I have assumed a power rating of 1,750W. Five minutes of use would consume 146 Wh.

Electric shower

Electric showers are high-power appliances, rated between 7,500W to 11,500W. Specific models of 7.2 kW, 7.5 kW, 8.5 kW, 9.5 kW, 10.5 kW, and 11.5 kW are typical.

I have assumed a 9,500W model here. A 10-minute shower at 9,500 watts would consume 1,583 Wh.

Electric shower (with a heat pump)

An electric shower with hot water sourced from a heat pump will use less electricity.

If we assume a heat pump with a Coefficient of Performance (COP) of 3, producing the same heat output would use around 3,000 Wh per hour. Some very efficient models can achieve less than this; often closer to 2,000 Wh.

Gas-powered shower

If we take the gas equivalent of an electric shower (rated at 9500W) and assume a boiler efficiency of 90%, we get around 10,500W in energy input equivalents. A 10-minute shower would consume 1,759 Wh.

Electric fan

Standard fans typically use 30-75 watts, with 50 watts being a reasonable average.

Small desk heater

Small portable electric heaters typically range from 400 to 1,000 watts. Here I’ve assumed a wattage of 750W. Using this for one hour would consume 750 Wh.

Space heater

A medium space heater typically operates at around 1,500 watts (ranging from 1,000 to as much as 3,000 for large ones). That means using one for an hour would consume 1,500 Wh.

Electric heat pump (single room)

Modern air-source heat pumps for single rooms (mini-splits) typically consume 600 to 1000 watts of electricity per hour of heating. This would be converted into around 1,800 to 3,000 Wh of heat.

Here we are assuming a Coefficient of Performance (CoP) value of around 3, which means 3 units of heat are generated per unit of electricity input.

These calculations are very sensitive to weather conditions, temperature settings, and the insulation of the house. These values might be typical for a moderate climate (such as the UK) in winter. In slightly warmer conditions, energy usage will be lower. In colder conditions, it would be higher.

The power draw can also be a bit lower than this once the heat pump is running.

Here, I’ve assumed they consume 800Wh of electricity per hour. That would supply 2,400Wh of heat.

Gas heating

We will assume our gas heating needs to supply the same amount of heat as our heat pump: 2,400 Wh.

A gas boiler is around 90% efficient, so the energy input needed would be 2,700 Wh (2,400 * 90%).

Again, this is very sensitive to the specific boiler system, climate and heating requirements.

Electric heat pump (3-bedroom house)

We can’t get a whole house figure by simply multiplying by the number of rooms. Energy consumption will depend a lot on the heat loss and fabric of the house.

In the UK, a 3-bedroom house has an area of around 90m². A building of this size might have a heat loss of around 50 to 100 W/m². We’ll say 75 W/m². That would mean 6,750W of heat is required (90m² * 75 W/m²).

Getting this from a heat pump with a CoP of 3 would consume 2,250Wh of electricity per hour (6750 / 3). This is what I’ve assumed in our calculations. In reality, the consumption is probably lower as energy draw reduces once the heat pump is up and running.

Gas heating (3-bedroom house)

We’ll use the same assumptions as above for a heat pump. We need to supply 6,750W of heat for the house.

Getting this from a 90% efficient boiler would consume 7,500Wh of gas per hour.

The average household in the UK uses around 31,000Wh of gas per day. That’s equivalent to 4–5 hours of heating (a bit less if their daily total includes a gas shower etc.). In winter, these heating hours will likely be higher, and during the summer, close to zero.

I think 7,500Wh of gas per hour therefore seems reasonable (but very sensitive to a specific household’s circumstances).

Air conditioning

Air conditioning units for single rooms typically use 800 to 1,500 watts. I’ve assumed 1,000W in these calculations.

The actual energy usage will be very sensitive to climate conditions. Warmer, and especially humid climates make AC units much less efficient. Running one in a moderate, drier climate would use much less.

They can also consume less energy once they’re up-and-running, so they’re not always going at maximum power draw.

7. Driving

Using an e-bike

Electric bicycles typically consume between 10 to 30 watt-hours per mile depending on speed, the cycling conditions, and how high the level of electric assist is. For light assist on flat terrain, it’s around 8 to 12 Wh; for moderate, around 12 to 18 Wh; and for heavy assist on hilly terrain it can reach 30 Wh per mile.

I’ve assumed a value of 15 Wh per mile.

Using an e-scooter

Electric scooters typically consume 15-30 watt-hours per mile depending on the model and conditions. Here, I’ve assumed a usage of 25 Wh per mile.

Driving an electric motorbike

Electric motorbikes typically consume 100 to 250 watt-hours per mile depending on the model, driver weight and conditions. Real-world tests of motorbike efficiency find efficiencies of around 100 Wh per mile for moderate urban driving. People report higher usage when driving at higher speeds or motorway driving.

Here I’ve assumed around 150 Wh per mile.

Driving a petrol motorbike

Petrol motorbikes can consume between 50 and 100 miles per gallon. Let’s take an average of 75mpg. A gallon is around 4.5 litres, so 75mpg is equivalent to 0.06 litres per mile.

The energy content of petrol is around 32 MJ per litre (or 8.9 kWh per litre). That equates to 0.53 kWh per mile (8.9kWh per litre * 0.06 litres per mile). Driving one mile uses around 530 Wh per mile.

In terms of energy inputs, this means an electric motorbike is 3 to 4 times as efficient as a petrol one.

Driving an electric car

Electric vehicles average approximately 0.3 kWh (300 Wh) per mile. However, this can range from 200 to 400 Wh per mile depending on the type of vehicle, driving conditions and speed.

Driving a petrol car

Petrol cars average around 40 miles per gallon (ranging from around 25 to 50).

Taking an energy density of ~40 kWh per UK gallon for petrol, there are around 40.5 kWh in a UK gallon (there are 4.546 litres in a gallon * 8.9kWh per litre).

This means a petrol car uses around 1kWh (1,000 Wh) per mile. This means an electric car is around 3 to 4 times more efficient, since it has far less energy losses from the engine, heat production, and braking.

9. Gardening

Electric lawnmower

Most corded electric lawnmowers have an energy rating between 1000W and 2000W. Here I have assumed 1500W.

Petrol lawnmower

Petrol lawnmowers are much less efficient than their electric equivalents, as much less input energy is converted into turning the blades.

A standard petrol lawnmower uses around 1 litre of petrol an hour (slightly less in more efficient models). Since the energy content of petrol is 8.9kWh per litre, they therefore use 8,000 to 10,000 Wh per hour. Here I have assumed 9,000 Wh.

Electric strimmer

Standard power strimmers range from around 250 watts to 700 watts. Smaller models will only be suitable for short grass.

Here I’ve assumed 500 watts.

Gas strimmer

Gas power strimmers are less efficient than electric models.

Data on this was hard to find, but a standard one probably consumes around 0.4 litres of petrol per hour. Since the energy content of petrol is 8.9kWh per litre, they therefore use around 3,500 Wh per hour in energy equivalents.

Pressure washer

Pressure washers typically have a power rating between 1,500 and 3,000 watts. For this tool, I’ve assumed 2,000 watts as standard.

Per hour, they will use 2,000 Wh when used continuously. Most people will take breaks and pauses during this time, so you should take that into account. If you break half the time, and use one for an hour, then the energy use is equivalent to half an hour (1,000 Wh).

Change log

I appreciate all of the feedback and comments from users. I continue to implement fixes and updates based on these suggestions.

Here is a log of changes and improvements.

03/03/2026

• Fixed a bug that showed incorrect cost calculations for gas products (e.g. gas oven and shower) for some country selections.

27/02/2026

• Added default pre-selections when the tool initially opens, to give people a sense of differences across products. This means they’re not facing a completely blank slate.
• Improved the visual design of the main chart to make it clearer and less cluttered.

24/02/2026

• For users with slower connections, the product list would load slowly and if they searched for products earlier, no options would appear. This has been fixed.

22/02/2026

• Added Dehumidifer, Power Strimmers, Power Washer, and Electric shower (with heat pump) as new selection options.
• Updated figures for Streaming Netflix and YouTube. The previous figure of 18 – 20 Wh per hour did not accurately reflect the marginal increase in electricity use for streaming. This figure is significantly lower.

19/02/2026

• Updated figures for “MacBook Pro”. Previous figures assumed a power draw of 70 watts, which is how much is used during intensive tasks such as photo or video editing, or gaming. For everyday tasks such as email, browsing and watching video, it’s closer to 20 watts.
• Updated figures for “Using an e-bike”. Previous figures assumed a usage of 25 watt-hours per mile. This is more reflective of heavy assistance on fairly hilly terrain. Moderate assist is closer to 15 watt-hours (which is the figure I now use).

17/02/2026

• Added clearer units for mobile phone charging and fridge-freezers (per day)
• Updated figures for “Electric oven” and “Gas oven”. Previous figures assumed a maximum power draw when it’s on. Ovens tend to cycle on and off once they’re at the desired temperature. I have therefore applied a 0.55 factor (50-60%) to account for this
• Added notes to emphasise that the appropriate time period for comparison is one day
• Added the option to switch between kilometres and miles for cycling and driving

16/02/2026

• Fixed checkbox selection; this was not working on some browsers/devices
• Improved dimensions and labelling on mobile devices
• Limited selection to 12 products at a time (more than this becomes unfeasible for visualisation)
• Added “Clear all selections” button at the top
• On mobile, the chart now appears at the top (above the checklist) for easier access
• The URL of the chart now updates based on the user selection. This means a specific configuration can be shared with others. Copy the URL from the browser bar, or use the “Share” button in the bottom-right
• An image of the chart can now be downloaded. Use the “Share” button in the bottom-right