Electricity Bill Calculator

Electricity Bill Calculator - How to Calculate Your Monthly Bill and Cut Costs

Most people receive their electricity bill every month without really understanding what they're paying for. They know the total number, but not which appliances drove it up. This calculator makes that visible: add every appliance in your home, enter the wattage and how many hours a day you use it, and you'll see a ranked breakdown of exactly which devices are costing you the most - and how much you'd save by changing each one's usage.

The Formula - How Electricity Bills Are Calculated

Every electricity bill is calculated using one core formula: kWh = Watts × Hours per Day × Days ÷ 1,000. The result is your energy consumption in kilowatt-hours (units). Multiply by your rate per unit to get the cost for that appliance for the period.

The division by 1,000 converts watts to kilowatts - because kWh means kilowatt-hours, not watt-hours. A 100W bulb uses 0.1 kW, so running it for 10 hours gives 0.1 × 10 = 1 kWh. Your meter counts kWh, which are the "units" on your electricity bill.

Typical Wattage of Common Home Appliances

Knowing typical wattages helps you estimate consumption even without checking the label. Here are the most common appliances and their realistic power consumption:

India Electricity Rates and Slab System - State by State

India uses a tiered (slab) pricing system for residential electricity - the more you consume, the higher your per-unit rate. This calculator uses a flat rate for simplicity, but understanding slabs helps explain why your bill increases disproportionately in summer when AC usage spikes.

Common slab structure (rates vary significantly by state):

• First 100 units: ₹3–5 per unit (low slab - subsidised)
• 101–200 units: ₹5–7 per unit
• 201–500 units: ₹7–9 per unit
• Above 500 units: ₹8–12 per unit (high slab)

States with notably different rates: Delhi (tiered with free 200 units for many households), Tamil Nadu (subsidised for BPL households), Maharashtra (higher urban rates in Mumbai), Karnataka, and Uttar Pradesh each have different SERC-approved tariff schedules. For exact rates, check your DISCOM's website or your bill's rate schedule.

Why Air Conditioning Dominates the Summer Bill

An air conditioner is by far the highest-consumption appliance in most Indian homes. A 1.5-ton AC draws approximately 1,500W and is often the single appliance accounting for 40–65% of a household's summer bill. The cumulative impact is significant:

• 8 hrs/day × 30 days × 1,500W ÷ 1,000 = 360 kWh per month
• At ₹8/unit = ₹2,880/month for one AC
• For a 5-star BEE-rated AC vs 3-star: roughly 20–25% lower consumption = ₹576–720 saving per month
• Setting temperature to 24°C instead of 18°C: approximately 24% energy saving per degree (every degree cooler increases consumption by about 6%)

Regular AC servicing - particularly cleaning the air filter monthly - maintains peak efficiency. A clogged filter forces the compressor to work harder and can increase consumption by 10–15%.

Standby Power - The Electricity You're Paying For Without Knowing

Standby power (also called "vampire power" or "phantom load") is electricity consumed by devices when they appear switched off but remain plugged in. Devices with remote controls, digital displays, or charging indicators always draw some power in standby.

Typical standby consumption per device:

• Set-top box / DTH receiver: 10–18W (often the worst offender - runs 24/7)
• LED television: 1–5W in standby
• Microwave with digital clock: 2–5W
• Phone charger with no phone: 0.1–2W
• Desktop computer in sleep mode: 5–15W

A set-top box at 15W running 24/7 for 30 days uses: 15 × 24 × 30 ÷ 1,000 = 10.8 kWh = ₹86/month. It might seem small, but across all standby devices, a typical household wastes 50–100W constantly in standby - adding ₹300–800 per year to the bill for nothing.