How to Check AC Electricity Use and Estimated Bills on KEPCO ON

Running an air conditioner for a long time does not mean you have to wait until the end of the month to find out your electricity bill. In KEPCO ON, you can check usage and billing details for registered electricity service contracts and enter the current meter reading to calculate the estimated bill through the next meter-reading date.

However, homes that contract directly with KEPCO and high-voltage apartments where the entire apartment complex is covered by a single contract have different inquiry methods and entities responsible for final settlement. When reviewing an estimate, you should check the contract type, meter-reading date, progressive rate tier, and the management office’s allocation criteria together.

Information to Prepare Before Checking

Checking the following information in advance will make inquiries and calculations easier.

• Customer number: Find it on your KEPCO electricity bill or in the electricity service contract information in KEPCO ON.
• Building and unit numbers: These may be required to check the estimated bill for an individual household in a high-voltage apartment.
• Previous meter reading: Find it on the previous bill or apartment maintenance fee statement.
• Current meter reading: Check the current number directly on the household meter.
• Meter-reading date or usage period: The actual usage period is more important than the billing month.
• Contract type: Basic charges and energy charges differ depending on the contract, such as residential low-voltage or residential high-voltage service.

If you do not know the customer number, households that contract directly with KEPCO can find it on a previous bill or in KEPCO ON. If the entire apartment complex has a contract with KEPCO, it is more accurate to ask the management office about the apartment’s customer number, how to check the household meter, and the electricity billing contract arrangement.

Checking Usage and the Estimated Bill in KEPCO ON

The screen layout and menu names in KEPCO ON may change, but the basic procedure is as follows.

Homes Contracting Directly with KEPCO

1. Access KEPCO ON, log in, and complete identity verification.
2. Register the customer number in the electricity service contract management menu.
3. Check monthly usage and billing details in the usage and billing inquiry menu.
4. Calculate current usage that has not yet been billed in the home electricity bill preview.
5. Enter the previous meter reading, current meter reading, and meter-reading information.
6. Check usage to date and the estimated bill in the calculation results.

Usage information may be provided automatically for meters that support remote reading. However, due to delays in communication and aggregation, the latest usage shown on the screen may not exactly match the number on the meter.

Households in High-Voltage Apartments That Do Not Contract Directly with KEPCO

In a typical high-voltage apartment arrangement, KEPCO bills the entire apartment complex’s usage under a single contract, and the management office divides the usage among households and reflects it in their maintenance fees. Such households may not have individual customer numbers or may be unable to link the contract using KEPCO ON’s standard customer registration process.

1. Check the apartment’s customer number and contract arrangement on the maintenance fee statement or with the management office.
2. In the KEPCO ON home electricity bill preview, select the inquiry type for high-voltage apartments.
3. Enter the information requested on the screen, such as the apartment customer number, building and unit numbers, and meter reading.
4. Treat the calculated amount as an estimate for reference and check the final amount on the maintenance fee statement.

Depending on the apartment’s system or contract arrangement, household information may not be available through the official calculation screen. In this case, you must use the household usage and billing calculation criteria provided by the management office.

Why the Estimate and Actual Maintenance Fee May Differ

The KEPCO ON result is an estimate calculated based on the usage entered and KEPCO’s rate system. The actual bill may differ for the following reasons.

Therefore, KEPCO ON calculation results for high-voltage apartments should be understood as reference values for electricity used exclusively by the household. If the electricity section of the maintenance fee includes common-area electricity charges, it cannot be directly compared with the KEPCO ON estimate.

Summer Progressive Rate Tiers for July–August and Meter-Reading Dates

Residential electricity uses a progressive rate structure in which the rate rises by tier as usage increases. Under the standard summer criteria, the progressive rate tiers for electricity used in July and August are expanded as follows.

The boundaries in this table describe usage tiers, and the actual rates may differ depending on whether residential low-voltage or high-voltage service applies and when they take effect. Calculations should prioritize the latest rates reflected in KEPCO ON.

Why You Should Check the Usage Period Rather Than the Billing Month

A bill received in August does not necessarily cover only electricity used from August 1 through 31. For example, if the meter-reading date is the 15th of every month, the billing period generally runs from the day after the previous month’s meter-reading date through the current month’s meter-reading date.

If the usage period spans summer and non-summer seasons, the seasonal tiers may be divided and applied according to KEPCO’s calculation criteria. When comparing bills, do not look only at the billing month; also check the usage period, meter-reading date, and number of usage days.

Calculating an Air Conditioner’s Monthly Electricity Usage

An air conditioner’s monthly electricity usage can be roughly calculated using the power consumption shown on the product and its operating time.

Monthly usage (kWh) = Power consumption (W) ÷ 1,000 × Hours of use per day × Number of days used × Load factor

The load factor is a simplified value representing the proportion of time the air conditioner actually operates at the stated power consumption level. In fixed-speed models, the compressor repeatedly switches on and off, while in inverter models, power consumption continuously changes according to the indoor and set temperatures. This makes it difficult to determine an exact load factor in advance.

Calculation Examples

The values below are assumptions intended to demonstrate the calculation method, not averages by product type. Actual calculations should use the rated cooling power consumption shown on the product’s energy efficiency label or nameplate.

For the window air conditioner, the calculation is 0.9kW × 8 hours × 30 days × 0.6 = 129.6kWh.

Efficiency should not be assumed based solely on the product type. Even among wall-mounted or window models, actual consumption can vary significantly depending on cooling capacity, whether the unit uses an inverter, installation conditions, outdoor temperature, room size, and insulation performance.

The Correct Way to Estimate Additional Air-Conditioning Costs

Multiplying air-conditioner usage by a single price per kWh does not properly account for progressive rates. A more accurate method is to compare the difference between the following two amounts.

1. Calculate the electricity bill using the household’s estimated monthly usage excluding the air conditioner.
2. Add the air conditioner’s estimated monthly usage and calculate it again.
3. Treat the difference between the two estimated bills as the additional cost of using the air conditioner.

For example, if a household’s existing usage is already close to the upper limit of Tier 1, some of the air conditioner’s usage may fall into Tier 2 or Tier 3. Conversely, households with low baseline usage may incur different additional charges even when using the same air conditioner for the same amount of time because their progressive rate tier composition differs.

Checklist for Reading Inquiry Results Accurately

• Confirm that the customer number on the inquiry screen matches the actual address.
• Check the meter-reading start and end dates rather than the billing month.
• Verify the usage by subtracting the previous reading from the current meter reading.
• If the meter has a separate multiplier, do not calculate it arbitrarily; check the criteria on the bill or with the management office.
• Confirm whether residential low-voltage or high-voltage service applies.
• In apartments, distinguish between household-only electricity and common-area electricity.
• Account for usage that will be added through the meter-reading date after the estimate is calculated.
• Confirm the final amount payable on the KEPCO bill or maintenance fee statement.

During extreme heat, it is also important not to excessively limit air conditioning in an effort to reduce costs. In particular, households with people at high risk of heat-related illness, such as older adults, infants, young children, and people with chronic illnesses, should prioritize health and safety and manage their budget by checking usage frequently.