How to Calculate Electricity Units and Estimate Your Next MEPCO Bill

“How many units will my bill be?” is usually easier to answer than “How many rupees will I pay?” Units come from electricity use recorded by the meter. The rupee amount depends on the tariff category, slabs, taxes, surcharges, adjustments, arrears, and payment timing.

That difference is important. A household can estimate its next consumption fairly well and still receive a different final bill because a tariff notification or monthly adjustment changed. The useful goal is not a fake exact prediction. It is a transparent estimate that lets you spot an unusually high reading early and understand which part of the bill needs checking.

What is one electricity unit?

On a residential electricity bill, one unit generally means one kilowatt-hour (kWh). It is the energy used by a 1-kilowatt load running for one hour, or a 100-watt load running for ten hours. The meter records accumulated energy, not simply the number of appliances in the house.

For example, a 1,000-watt electric heater operating for two hours uses approximately 2 kWh, or two units, before considering any measurement or billing detail. A 100-watt fan running for five hours uses approximately 0.5 kWh. The nameplate wattage and the actual running time both matter.

The basic meter-reading calculation

For a normal meter, start with the current reading and subtract the previous reading:

Units consumed = Current meter reading − Previous meter reading

If last month’s reading was 12,450 and this month’s reading is 12,612, the recorded consumption is:

12,612 − 12,450 = 162 units

The bill’s reading dates should be checked alongside the numbers. A bill covering 35 days may contain more usage than a bill covering 28 days even if the household’s daily routine did not change. MEPCO’s billing guidance says meter readings record the energy consumed during the billing cycle and identifies the reading date, meter reading, and units consumed as key information.

Do not reset a meter, open the meter box, or remove a seal to obtain a reading. Photograph the display from outside the enclosure, preferably with the date and meter number visible. For a digital meter, the display may cycle through multiple values. Use the kWh or energy reading, not a voltage, current, maximum-demand, or error screen.

What if the bill shows a multiplying factor?

Some installations have a multiplying factor because of their metering arrangement. In that case, the meter-register difference may not equal the billed units directly. A simplified calculation is:

Billed units = (Current reading − Previous reading) × Multiplying factor

For example, a register difference of 80 with a factor of 2 would produce 160 billed units. Do not assume a factor from a neighbour’s bill. Check the factor printed on your own bill and ask MEPCO if it is missing or unclear. Many ordinary household connections have no extra factor, but higher-load or specialised metering can be different.

Estimating appliance units

To estimate an appliance’s energy use, convert watts to kilowatts and multiply by operating hours:

Estimated units = (Appliance watts ÷ 1,000) × Hours used

For a monthly estimate:

Monthly units = (Watts ÷ 1,000) × Hours per day × Days used

Suppose a 100-watt fan runs for 10 hours a day for 30 days:

(100 ÷ 1,000) × 10 × 30 = 30 units

Suppose a 1,200-watt iron is used for 45 minutes on each of 20 days:

(1,200 ÷ 1,000) × 0.75 × 20 = 18 units

Add each appliance estimate to create a rough monthly total. Use the wattage printed on the nameplate where possible. An appliance that cycles on and off, such as a refrigerator or inverter air-conditioner, may consume less than its maximum rated wattage over a full hour. An old or poorly maintained appliance may also behave differently from the label. Treat the calculation as a planning estimate, not a laboratory measurement.

A worked household example

Consider a small household with the following estimated monthly use:

Appliance	Assumption	Approximate monthly units
Two 80 W fans	8 hours/day for 30 days	38.4
Five 10 W LED bulbs	6 hours/day for 30 days	9
1,200 W iron	45 minutes/day for 20 days	18
100 W refrigerator average	10 equivalent hours/day	30
750 W water pump	1 hour/day for 20 days	15
100 W television	5 hours/day for 30 days	15
Estimated total		125.4

This household might expect roughly 125 units from the listed loads. It should then add anything omitted: an air-conditioner, washing machine, computer, battery charger, microwave, electric kettle, water dispenser, or standby equipment. It should also allow for changes in weather and routine. One additional 1,500 W heater running for two hours each day for 10 days adds about 30 units on its own.

The most useful comparison is with the meter. If the meter shows 190 units, the 65-unit difference is a prompt to look for an omitted or underestimated load, a longer billing period, a reading error, or an account detail such as a multiplying factor. It is not proof of overbilling by itself.

Estimating the energy-charge part of the bill

Once you have an estimated number of units, identify the account’s tariff category. A residential non-ToU protected account is not priced in the same way as a non-protected account, and a TOU account may separate peak and off-peak usage. Commercial and other connection categories have their own schedules.

The simplest illustration is:

Estimated energy charge = Estimated units × Applicable variable charge per unit

But a slab tariff may apply different rates to different portions of consumption. If the applicable schedule has one rate for the first band and another for the next band, do not multiply every unit by the higher rate without checking the notified rules. Some schedules also contain a one-slab benefit or other billing treatment. Use the tariff applicable to the bill month.

As an illustration only, NEPRA’s February 2026 uniform residential schedule listed Rs. 10.54 per kWh for the 1–100 protected band and Rs. 13.01 for the 101–200 protected band. A customer cannot turn those two figures into an exact payable bill without knowing the account category, current notification, and the treatment of all other charges. Rates and adjustments can change after publication.

Why the final bill is different from units multiplied by a rate

The energy charge is only one part of the bill. Depending on the account and bill month, the document may include:

• electricity duty or government taxes;
• GST and other applicable levies;
• surcharges and financing or policy components;
• Fuel Charges Adjustment (FCA);
• Quarterly Tariff Adjustment (QTA) or other periodic adjustments;
• fixed or minimum charges where applicable;
• arrears, previous balance, or an adjustment from an earlier correction;
• late-payment surcharge if the previous bill was paid after the due date.

This is why a 150-unit bill can be higher than a rough estimate based on a per-unit figure found online. It is also why the same number of units can produce different totals in different months. When forecasting rupees, estimate a range and label the assumptions instead of publishing an exact-looking number.

A practical monthly forecasting method

Use this five-step process:

1. Record the meter reading on the same day each week.
2. Subtract readings to find the recent daily average.
3. Multiply the daily average by the expected number of days in the next billing cycle.
4. Compare the forecast units with the account’s tariff bands and history.
5. Apply the current tariff and add a separate allowance for taxes, adjustments, and other bill lines.

If the meter has recorded 4 units per day for the last 20 days, a 30-day cycle would suggest roughly 120 units, assuming the routine remains stable. A heatwave, school holiday, guest visit, or water shortage can change the estimate quickly. For a TOU meter, record peak and off-peak registers separately rather than combining them too early.

How to find an unexpected increase

Start with the readings and dates, not the total amount. Compare the current reading with the physical meter. Confirm that the bill’s previous reading matches the prior bill and that the billing period is reasonable. Then inspect the 12-month consumption history if available.

Common explanations include air-conditioner or heater use, a water pump running longer, a defective appliance, a missed or estimated reading followed by an actual reading, a meter replacement, a multiplying factor, or a tariff/account-category change. A large amount can also come from arrears or adjustments even when units are ordinary.

If the numbers do not reconcile, save the bill and photographs, then contact MEPCO or register a PITC billing complaint. Give the reference number, meter number, reading dates, current and previous readings, and the exact calculation that does not match. A clear record is more useful than a general complaint that the bill is “too high.”

Frequently asked questions

How many units does a 1,000-watt appliance use in one hour?

Approximately one unit, because 1,000 watts equals 1 kilowatt and one hour at that load equals 1 kWh. Actual billed use depends on the appliance’s operating cycle and the meter reading.

Why do my meter units differ from my appliance estimate?

You may have omitted loads, underestimated running time, ignored standby consumption, or used the wrong wattage. Also check the billing dates, meter factor, and whether the appliance cycles rather than running at full power continuously.

Can I calculate my exact MEPCO bill from units?

Usually not without the current tariff and all account details. Units help estimate the energy component, but taxes, surcharges, adjustments, fixed charges, arrears, and late-payment entries affect the final amount.

What does “estimated” or “est” mean on a bill?

It indicates that the bill was not based on a normal verified meter reading. Ask MEPCO how the estimate was calculated and request correction if the actual meter reading is available.

How can I estimate a TOU bill?

Track peak and off-peak readings separately, apply the relevant TOU components, and add the other bill lines. Do not use a single residential rate for both registers unless the current schedule says so.

What should I do if the previous reading on my bill is wrong?

Photograph the meter, preserve the previous bill, and contact MEPCO customer service or PITC with the reference number and reading dates. Ask for a reading and billing-history verification.

Editorial source notes

• MEPCO, Chapter 6: Meter Reading and Billing: https://www.mepco.com.pk/sites/default/files/Upload/PDF/Chaptar-6.pdf
• NEPRA, Decision regarding Federal Government Motion and Policy Guidelines for Rationalization of Tariff, 11 February 2026: https://www.nepra.org.pk/tariff/Tariff/Ex-WAPDA%20DISCOS/2026/TRF-100%20XWDISCOS%20AND%20KE%20RATIONALIZATION%20OF%20TARIFF%2011-02-2026%202935-57.pdf
• NEPRA, consumer electricity bill and tariff explanation: https://nepra.org.pk/consumer%20affairs/Electricity%20Bill.php
• MEPCO customer service: https://www.mepco.com.pk/customer-services
• PITC Customer Complaint Management System: https://ccms.pitc.com.pk/complaint

Tariffs, taxes, and adjustment components can change.