Calculate air conditioner cost from electrical power
Estimate running cost from electrical input, operating hours and an applicable electricity rate.
Back to calculator ↑Read the right appliance number
Find electrical input in watts on the label or measure it. If the label gives a range, use a value relevant to your operation. BTU/h is cooling capacity, not input watts.
If the nameplate lists maximum and nominal input, do not silently treat the maximum as all-day consumption. Record the model, mode, set temperature and measurement period so later comparisons use similar conditions. Room size, sun exposure and on/off behavior can all change the measured average.
Calculate energy and cost
Multiply input watts by hours and the duty fraction, then divide by 1,000 for daily kWh. Multiply by days. The default bill method divides bill amount by bill kWh; MEA/PEA, TOU and custom rate methods are also available.
The time fraction describes equivalent time at the entered power. For example, eight hours switched on with 50% equivalent operation means four full-power hours in this simplified model. If you already have meter kWh/day, compare it with the daily output and calibrate the fraction before projecting a month.
Worked example at a custom rate
1,000 W × 8 hours × 70% = 5.6 kWh/day. Over 30 days that is 168 kWh. At a separately entered custom THB 4.5/kWh, the estimate is THB 756/month. The starting bill inputs, THB 1,200 for 300 kWh, instead give THB 4/kWh and THB 672/month.
THB 756 is the estimated energy charge for this appliance, not the whole household bill. Under the same assumptions, reducing daily use from eight to six hours changes 168 to 126 kWh/month and THB 756 to THB 567. That difference is useful for comparing behavior, while actual bills can differ.
Check the limits
Inverter output varies through the day, and fixed bill charges may not change with use. Meter several days and replace the assumed inputs with measured values.
For a purchase, compare model-specific efficiency labels and test conditions; this calculator alone cannot rank air conditioners. If the bill has tiered energy charges, try the relevant marginal rate from your bill and label it as an assumption. Metering across several weather conditions gives a better planning estimate.
When testing a different tariff, hold hours and duty fraction constant first. Then change the operating schedule separately. This separates price effects from behavior. For hot and rainy months, use separate measured examples because duty fraction may change substantially.
Common questions
Can BTU/h go in the watts field?
No. Enter electrical input power in watts.
Is 70% a standard duty fraction?
No. It is an editable example assumption.
Does the rate include other bill items?
The bill method uses the bill average THB/kWh, including fees in that average. MEA/PEA and TOU options model an incremental charge using the listed tariff, Ft and VAT; check your bill and the displayed billing period.
Sources and calculation guidance
Check these against your chosen product’s label and instructions.