Electricity Cost Calculator
Enter power consumption (kW), hours of use per day, days per month, electricity rate, and number of units to calculate daily, monthly, and annual electricity costs.
Enter power consumption (kW), hours of use per day, days per month, electricity rate, and number of units to calculate daily, monthly, and annual electricity costs.
Watts ÷ 1,000 = kW
Average daily operation
Workdays or operating days
Same equipment running in parallel
From your utility bill
Use this in your workflow
Use this calculator to forecast facility operating costs, budget for utilities, or evaluate the cost-benefit of energy efficiency upgrades. Once you have your electricity cost baseline, use the ROI Calculator to compare the return on investing in LED lighting, HVAC upgrades, or other efficiency improvements. Browse all Free Business Calculators.
Worked example: office HVAC system
A typical scenario to help you understand the inputs and outputs.
| Input / Output | Value |
|---|---|
| Power consumption (kW) | 3.5 |
| Hours of use per day | 8 |
| Days per month | 22 |
| Number of units | 2 |
| Electricity rate ($/kWh) | $0.12 |
| Total daily kWh (3.5 × 8 × 2) | 56 kWh |
| Total daily cost (56 × $0.12) | $6.72 |
| Monthly cost (56 × 22 × $0.12) | $147.84 |
| Annual cost ($147.84 × 12) | $1,774.08 |
Interpretation: Running two 3.5 kW HVAC units for 8 hours per workday costs approximately $1,774 per year. If you reduce runtime to 6 hours per day, annual cost drops to $1,331. Upgrading to higher-efficiency units (2.5 kW each) would cut the bill to $1,267 annually.
When to use this calculator
- →Budgeting annual facility operating costs for offices, warehouses, or manufacturing
- →Evaluating the ROI of energy efficiency upgrades or equipment replacements
- →Comparing power consumption and cost of different equipment or systems
- →Forecasting utility costs for business plans or financial models
Common mistakes in electricity cost calculations
Forgetting to convert watts to kilowatts
If your equipment is rated in watts (W), divide by 1,000 to get kilowatts (kW). A 500 W microwave is 0.5 kW, not 500 kW. Entering the wrong unit will inflate your costs by 1,000 times.
Using peak power consumption instead of average
Equipment power consumption varies during operation — a motor draws high current at startup but less at steady state. Use the average or continuous power rating, not the peak inrush current.
Ignoring part-time usage and seasonal variation
HVAC, outdoor lighting, and some industrial equipment do not run at the same rate year-round. Adjust hours per day seasonally (e.g., heating in winter, cooling in summer) to get a more accurate annual estimate.
Not accounting for electricity rate increases
Most utility rates increase 2–5% annually. This calculator uses a static rate. For multi-year forecasts, factor in rate escalation or use a conservative high estimate.
Overlooking standby and phantom power
Equipment in standby mode still draws power — office equipment, servers, and powered-off devices on standby consume 10–15% extra energy. If your facility has many devices, factor in additional standby load.
Limitations
This calculator uses a single electricity rate and does not account for demand charges, time-of-use pricing, seasonal rates, or power factor penalties that commercial utilities may apply. It assumes constant power consumption and does not model standby power, efficiency degradation over time, or future rate escalation. Equipment power ratings should be verified on the nameplate or datasheet. These results are for planning purposes only — compare against actual utility bills to validate assumptions.
Frequently asked questions
How is electricity cost calculated?
Cost = Power (kW) × Hours per day × Days per month × Electricity rate ($/kWh) × Number of units. The result is monthly cost in dollars. For annual cost, multiply monthly cost by 12.
What is the difference between watts and kilowatts?
One kilowatt (kW) equals 1,000 watts (W). Equipment is often rated in watts, but electricity billing uses kilowatt-hours (kWh). Divide watts by 1,000 to convert to kW.
Why do I need to know days per month?
Days per month accounts for weekends, holidays, and seasonal variation in operating hours. An office HVAC might run 22 workdays per month, while a 24/7 production line runs 30 days per month.
Can I include multiple equipment types in one calculation?
This calculator handles one equipment type at a time. For a facility with multiple systems (HVAC, lighting, refrigeration), calculate each separately and add the results together.
Does this include demand charges?
No. This calculator covers energy charges (kWh usage). Commercial utilities may also charge demand charges ($/kW peak power) and other fees — check your utility bill for the full cost structure.
How accurate is this estimate?
The calculation is accurate if your power consumption, hours of use, and electricity rate are accurate. Compare your calculated cost against your actual utility bills to validate your inputs.