What Is a Unit of Gas and Electricity?
If you have ever looked at your energy bill and wondered what a unit actually means, you are not alone. This guide explains what a unit of gas and electricity is, how it is measured, and why it matters for what you pay — in plain English.
Understanding units is the foundation of understanding your energy bill. Once you know what a kWh is and how it relates to what you use at home, every other number on your bill starts to make sense.
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A kilowatt-hour, written as kWh, is the standard unit of energy used for billing both gas and electricity in the UK. One kWh is the amount of energy used by a 1,000-watt appliance running continuously for one hour.
Here are some everyday examples to make that concrete:
- A 1,000W electric heater running for 1 hour uses exactly 1 kWh
- A 100W light bulb running for 10 hours uses 1 kWh
- A 2,000W kettle boiling for 30 minutes uses 1 kWh
- A 50W TV running for 20 hours uses 1 kWh
Your energy bill multiplies the number of kWh you consumed by your unit rate in pence per kWh to calculate the usage portion of your bill.
What Is the Difference Between kW and kWh?
This is one of the most common points of confusion on energy bills. A kilowatt (kW) is a measure of power — how fast energy is being used right now. A kilowatt-hour (kWh) is a measure of energy — how much has been used over a period of time.
Think of it like driving. kW is your speed at any moment. kWh is the total distance covered. Your bill charges you for the distance travelled, not the speed.
How Is Electricity Measured?
Electricity is measured directly in kWh by your electricity meter. When you use an appliance it draws power in watts (W) or kilowatts (kW). Over time that power use adds up to kilowatt-hours. Your supplier reads the meter, calculates the kWh used since your last reading, and charges you at your unit rate.
How Is Gas Measured?
Gas is slightly more complicated. Your gas meter measures the volume of gas you burn — in cubic metres (m³) if you have a metric meter, or cubic feet (ft³) if you have an older imperial meter. However gas is billed in kWh, not in cubic metres.
Your supplier converts the volume reading to kWh using two values:
- Calorific value — the amount of heat energy in the gas, which varies slightly by region and is set by your supplier
- Conversion factor — a fixed number (1.02264) that accounts for the difference between volume at atmospheric and metering pressure
The calculation is: cubic metres × calorific value × 1.02264 ÷ 3.6 = kWh. This is why your gas meter reading and your billed kWh are never the same number. If you need to convert gas readings yourself use the Gas to Electricity Unit Converter.
Typical Appliance Energy Usage
Understanding how much energy different appliances use helps you see where your kWh are going. The table below shows typical electricity consumption for common UK household appliances at the current Ofgem rate of 24.70p per kWh.
| Appliance | Typical Power | kWh per Use | Cost per Use |
|---|---|---|---|
| Electric shower (9kW, 8 min) | 9,000W | 1.2 kWh | ~29p |
| Tumble dryer (cycle) | 2,500W | 2.5 kWh | ~61p |
| Electric oven (1 hour) | 2,000W | 2.0 kWh | ~49p |
| Washing machine (cycle) | 500–2,000W | ~1.0 kWh | ~25p |
| Dishwasher (cycle) | 1,200–1,500W | ~1.2 kWh | ~29p |
| Fridge-freezer (per day) | 100–200W | ~1.0 kWh | ~25p |
| Kettle (per boil) | 2,000–3,000W | ~0.1 kWh | ~2.5p |
| LED TV 55" (per hour) | 80–120W | 0.1 kWh | ~2.5p |
| LED light bulb (per hour) | 8–10W | 0.009 kWh | ~0.2p |
Estimated Cost per Use by Appliance (at 24.7p/kWh)
How Much Energy Does a Typical UK Home Use?
According to Ofgem, a typical UK household uses approximately 2,700 kWh of electricity and 11,500 kWh of gas per year. These are averages across all household sizes — a one-bedroom flat will use considerably less, a large detached house considerably more.
| Fuel | Annual Usage | Monthly Usage | Daily Usage |
|---|---|---|---|
| Electricity | 2,700 kWh | 225 kWh | 9.6 kWh |
| Gas | 11,500 kWh | 958 kWh | 32.9 kWh |
What Are the Current Unit Rates?
Unit rates in the UK are regulated by the Ofgem price cap. From April 2026 the typical rates are:
| Fuel | Unit Rate (p/kWh) | Standing Charge (p/day) |
|---|---|---|
| Electricity | ~24.70p | ~61p |
| Gas | ~5.70p | ~31p |
Your actual rates depend on your supplier, tariff, and region. Always check your bill for your exact figures. For more on how the price cap works see our guide to What Is the Ofgem Price Cap?
Where to Find Your Unit Rate
Your unit rate is shown on your energy bill, usually on the first or second page, listed as pence per kWh (p/kWh) separately for gas and electricity. You can also find it in your online account or supplier app. For a full walkthrough of how to read your bill see How to Read Your Energy Bill.
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Frequently Asked Questions
What is a unit of electricity?
One unit of electricity is one kilowatt-hour (kWh) — the energy consumed by a 1,000-watt appliance running for one hour. Your meter counts these up and your bill charges you per unit at your unit rate.
What is a unit of gas?
Gas meters measure in cubic metres (m³) or cubic feet (ft³). Your supplier converts this volume to kWh using the calorific value of the gas before billing you — so a unit of gas on your bill is also a kWh.
Why is my gas meter in m³ but my bill in kWh?
Gas meters measure volume because that is the easiest physical measurement to take. But the energy content of gas varies slightly, so suppliers convert volume to kWh to ensure you are billed for the actual energy delivered rather than the volume.
What is the difference between kW and kWh?
kW (kilowatt) is power — the rate of energy use at any instant. kWh (kilowatt-hour) is energy — the total consumed over time. Your bill charges kWh, not kW.
How many kWh does a typical UK home use?
Ofgem estimates around 2,700 kWh of electricity and 11,500 kWh of gas per year for a typical household. This varies significantly by size, insulation, and heating type.
Summary
- A unit of energy is one kilowatt-hour (kWh) — the standard measure for both gas and electricity billing
- Electricity meters measure kWh directly; gas meters measure volume which is then converted to kWh by your supplier
- kW is the rate of power use at any moment; kWh is the total energy consumed — your bill charges kWh
- A typical UK home uses 2,700 kWh of electricity and 11,500 kWh of gas per year
- Your unit rate is shown on your bill in pence per kWh and is capped by Ofgem for standard variable tariffs
- To calculate exactly what your usage is costing you, use the Energy Unit Cost Calculator →