Electricity Cost Calculator

How many units (kWh) your appliances use and what your bill will be — with the rates printed on your own bill.

Result
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    How it works

    The method

    Energy (kWh) = watts × hours ÷ 1000; a 'unit' on a bill is 1 kWh. Bills price units one of three ways: one price for all, slab by slab (telescopic), or all units at the price of the slab reached — then add fixed, demand, standing and percentage charges.

    Worked example

    Slabs 75 at 5.26, 200 at 7.20, 300 at 7.59 and 250 units used: 75 × 5.26 + 125 × 7.20 + 50 × 7.59 = 394.50 + 900 + 379.50 = 1674 for energy. Two fans of 75 W for 8 hours: 75 × 8 × 2 ÷ 1000 = 1.2 kWh a day.

    Common mistakes

    Don't multiply watts by hours and call it kWh — divide by 1000. Slabs are usually counted per month, so a 60-day bill has bigger slabs. Use the rates on your latest bill: tariffs change.

    Questions & answers

    How do I find an appliance's watts?

    It is printed on the label or plate on the back or bottom, or in the manual (W or kW; 1 kW = 1000 W). For an air conditioner, use the input power, not the cooling capacity.

    What is the difference between telescopic and non-telescopic slabs?

    Telescopic: the first units are charged at the first slab's price, the next ones at the next price, and so on. Non-telescopic: every unit is charged at the price of the slab your total falls in. Your bill or your company's tariff says which one you have.

    Why doesn't the result match my bill exactly?

    Check that every charge on your bill is entered: fixed charges, demand, standing charge, fuel adjustment and percentages, and that the slabs are for the same number of days. Some companies also round each line to whole money.

    Are the rates of my country built in?

    No. Rates change often, and an old rate would give a wrong bill, so you type the rates from your latest bill. You can save them on this device with Save these rates.

    How do I read a meter that went back to zero?

    Enter the number of wheels or digits on the meter. With 5 digits, from 99850 to 120 is 100000 − 99850 + 120 = 270 units.

    Does this page send my numbers anywhere?

    No. Everything is calculated on your device; saved rates stay in this browser only.

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