AC Cost Calculation Formula
Monthly Cost = [Power (watts) × Hours per Day × Days per Month × Electricity Rate ($)] / 1000
Simple Example
1.5 Ton AC (1500W), 8 hours/day, 30 days/month, $0.12 per unit:
= (1500 × 8 × 30 × 0.12) / 1000 = $43.20/month
Power Consumption by AC Type
1.5 Ton Non-Inverter (3-star): ~1500W
- 8 hours/day @ $0.12/unit = $43.20/month = $518/year
- 12 hours/day @ $0.12/unit = $64.80/month = $778/year
1.5 Ton Inverter (5-star): ~1000W
- 8 hours/day @ $0.12/unit = $28.80/month = $345/year
- 12 hours/day @ $0.12/unit = $43.20/month = $518/year
Difference: Inverter saves $173-260 per year for 1.5 ton AC
Seasonal Variation
Monthly costs vary by season. Summer bills are typically 2-3x higher than shoulder months (April, September).
Example for 1.5 Ton Inverter (1000W)
- April (hot): $57.60 (12 hours/day)
- June-August (peak): $86.40 (18 hours/day)
- September: $50.40 (11 hours/day)
- November-February: $10-20/month (minimal use)
Factors Affecting Your Actual Cost
Usage Patterns
- Morning (6-10 AM): Low usage, low cost
- Afternoon (12-6 PM): Peak usage, high cost
- Night (6-10 PM): Moderate usage
- Sleep mode: Lower cost
Room Conditions
- Good insulation: Lower cost (10-15% less)
- Poor insulation: Higher cost (10-15% more)
- Shaded room: Lower cost
- Direct sun exposure: Higher cost
Temperature Setting
- 24°C: Baseline cost
- 25°C: ~5% lower
- 26°C: ~10% lower
- 27°C: ~15% lower
Estimating Your Electricity Rate
Check your electricity bill for the rate per unit (kWh). Rates vary by region and can differ by time of use.
Typical Rates (varies by region)
- Rural areas: $0.08-0.10/unit
- Urban areas: $0.10-0.15/unit
- Peak hours: Higher rates in some regions
Cost Comparison: Different AC Sizes
| AC Size | Power (W) | 8 hrs/day Cost | 12 hrs/day Cost |
|---|---|---|---|
| 1 Ton (12,000 BTU) | 1000 | $28.80 | $43.20 |
| 1.5 Ton (18,000 BTU) | 1500 | $43.20 | $64.80 |
| 2 Ton (24,000 BTU) | 2000 | $57.60 | $86.40 |
Annual AC Cost Projection
Assuming summer months (May-September) are 5 months with high usage, shoulder months are 3 months with medium usage, and winter months are 4 months with minimal usage:
1.5 Ton Inverter AC Estimate
- Summer (5 months @ $57.60): $288
- Shoulder (3 months @ $28.80): $86.40
- Winter (4 months @ $10): $40
- Total Annual: ~$414
Cost Saving Tips
- Set temperature 2°C higher: Saves 10-15%
- Use timer function: Saves 20-30%
- Use ceiling fan together: Saves 5-10%
- Upgrade to inverter: Saves 30-40%
- Annual maintenance: Improves efficiency 5-10%
Conclusion
Calculate your actual costs using our online calculator. Knowing monthly expenses helps you choose the right AC and usage patterns to minimize bills.