How to Read Your Electricity Bill

What you need

A recent bill and, if you want to check it, the meter readings for the same period. The bill shows three things: how much energy you used, what each unit cost, and the fixed daily charge. Everything else on the bill is detail — these three are the bill.

Step 1 — Find the units (kWh)

The energy used is measured in kilowatt-hours, written kWh. One kWh is 1,000 watts used for one hour — a 100-watt bulb left on for ten hours, or a 2,000-watt heater for half an hour. Check the figure against your meter: the current reading minus the previous reading should match the units on the bill. If it does not, the bill may be estimated — ask your supplier for an actual reading.

Step 2 — Find the tariff

The tariff is the price per kWh — your rate, from your bill. Rates vary by supplier, by plan and by time of day, and they change over time, so never use a rate you found online: use the one printed on your own bill. Some plans charge different rates at different times of day (peak and off-peak); if yours does, the bill breaks the units down by rate, and each part is charged separately.

Step 3 — Find the standing charge

The standing charge is a fixed daily amount you pay regardless of how much energy you use — it covers the cost of the connection itself. It is shown per day on the bill, and the total is the daily charge multiplied by the number of days in the billing period. A bill with no standing charge is rare; a bill where it is hidden in the fine print is common.

Step 4 — Work out the total

Multiply the units by the tariff, then add the standing charge for the period. The electricity cost calculator does it: 350 kWh at $0.15 per kWh is $52.50, and a $0.50 standing charge over 30 days is $15.00, for a total of $67.50 — an average of $2.25 a day. The $0.15 tariff and the $0.50 standing charge are the calculator's example figures, not real rates: enter your own bill's numbers to check your own total.

Step 5 — Check where the energy goes

If the total surprises you, find out which appliances use the most. The energy usage calculator works out each appliance's kWh from its watts, its hours per day and the days in the period: watts × hours × days ÷ 1,000. A heater left on all day uses more than a television left on all evening, and the calculator shows you by how much.

Worked example

Energy used: 350 kWh. Tariff: $0.15 per kWh (the calculator's example rate). Energy cost: 350 × $0.15 = $52.50. Standing charge: $0.50 × 30 days = $15.00. Total: $52.50 + $15.00 = $67.50. Average per day: $67.50 ÷ 30 = $2.25. Those are exactly the numbers the electricity cost calculator gives you — with your own tariff and standing charge, it gives you your own bill.

Common mistakes

• Confusing kW with kWh. Kilowatts are power — how fast energy is used. Kilowatt-hours are energy — how much was used. A bill charges for kWh, not kW.
• Forgetting the standing charge. It is a real cost, and over a month it is often a fifth of the bill. A total without it is not the total.
• Comparing bills with different day counts. A 31-day bill is bigger than a 28-day bill for the same usage. Compare the average per day, not the headline total.

Safety

Reading a bill is safe work — there is nothing hazardous in this guide. Never open the meter, the meter box or the consumer unit yourself, and never try to change a meter reading: electrical work, including anything inside the consumer unit, is for qualified electricians. If a bill looks wrong, call your supplier and ask for an actual meter reading.

Try these calculators

• Electricity Cost Calculator — cost from units, tariff and standing charge.
• Energy Usage Calculator — kWh and cost for up to three appliances.
• Watt to kWh Calculator — watts and hours to kilowatt-hours.