The calculator multiplies each appliance's wattage by hours of daily usage to get daily kWh consumption (watts × hours ÷ 1000). This is then multiplied by 30 for monthly units and by your electricity rate per unit to estimate the monthly cost.

One unit of electricity equals 1 kilowatt-hour (kWh) — the energy consumed by a 1000-watt appliance running for 1 hour. For example, a 100-watt bulb running for 10 hours uses 1 unit. Electricity boards in India charge per unit, typically ₹3-8 depending on the state and slab.

Air conditioners (1500-2500W), water heaters/geysers (1500-3000W), electric ovens (2000-2500W), and washing machines with dryers (2000-2500W) are typically the highest consumers. Refrigerators consume less per hour but run 24/7, accumulating significant monthly usage.

Use star-rated (BEE) appliances, switch to LED lights, set AC at 24°C, use a solar water heater, unplug devices when not in use, and consider time-of-use tariffs if available in your area. Even upgrading from a 3-star to a 5-star AC can save 15-20% on cooling costs.