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CalcHub Blog
March 26, 20266 min read

How to Calculate Your Electricity Bill (And Reduce It)

Understand how electricity bills are calculated — units consumed, tariff slabs, fixed charges. Plus practical tips to reduce your monthly bill.

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Electricity bills are confusing by design. Between slab rates, fixed charges, duty, and surcharges, it's hard to tell what you're actually paying for. But the core math is straightforward: you're charged for the number of units (kWh) you consume, at rates that increase as you use more.

Here's how to calculate your bill, verify it, and bring it down. Use the calculators at CalcHub for quick energy consumption estimates.

How Electricity Units Work

1 unit = 1 kWh (kilowatt-hour) = running a 1,000-watt appliance for 1 hour. Formula: Units consumed = Wattage × Hours used × Days / 1,000
ApplianceWattageHours/DayMonthly UnitsMonthly Cost (₹8/unit)
LED bulb (10W)10W82.4₹19
Ceiling fan75W1227₹216
Refrigerator150W (avg)24108₹864
1.5 ton AC (5-star)1,200W8288₹2,304
1.5 ton AC (3-star)1,600W8384₹3,072
Washing machine500W115₹120
TV (LED, 43")80W614.4₹115
Desktop computer300W872₹576
Laptop65W815.6₹125
Electric geyser2,000W0.530₹240
Microwave1,200W0.259₹72
Iron1,000W0.515₹120

Understanding Tariff Slabs

Most Indian states use telescopic/slab tariffs — the rate per unit increases as you consume more:

Example slab structure (varies by state):
ConsumptionRate per Unit
0–100 units₹4.00
101–200 units₹5.50
201–300 units₹7.00
301–400 units₹8.50
Above 400 units₹10.00
For 350 units consumed:
  • First 100 units: 100 × ₹4.00 = ₹400
  • Next 100 units: 100 × ₹5.50 = ₹550
  • Next 100 units: 100 × ₹7.00 = ₹700
  • Next 50 units: 50 × ₹8.50 = ₹425
  • Energy charge: ₹2,075
Then add fixed charges (₹50–200/month), electricity duty (5–10%), and fuel surcharge.

The Real Cost Drivers

Air Conditioning (40–60% of summer bills)

AC is the single biggest electricity expense in most Indian homes. The difference between a 3-star and 5-star AC is significant:
AC TypeMonthly Units (8h/day)Monthly Cost
1.5T, 3-star384₹3,072
1.5T, 5-star288₹2,304
1.5T, inverter 5-star216₹1,728
A 5-star inverter AC saves ₹1,344/month over a 3-star non-inverter. Over a 5-month summer, that's ₹6,720/year — the price difference pays for itself in 1–2 years.

Geysers (Surprisingly Expensive)

A 2,000W geyser running just 30 minutes/day consumes 30 units/month. In winter, if two family members use it for 15 minutes each, twice daily, that's 60 units — ₹480+/month from one appliance. Solar water heaters pay for themselves in 2–3 years and last 15–20 years.

Old Refrigerators

A 10-year-old refrigerator might consume 150–200 units/month. A new 5-star inverter refrigerator of the same size uses 30–45 units. Replacing an old fridge often reduces total household consumption by 15–20%.

How to Read Your Electricity Bill

Key numbers to check:

  1. Sanctioned load — your approved connection capacity (1 kW, 2 kW, etc.). Higher load = higher fixed charges.
  2. Units consumed — current meter reading minus previous reading.
  3. Energy charges — units × applicable slab rates.
  4. Fixed/demand charges — monthly charge based on sanctioned load.
  5. Electricity duty — state levy, usually 5–10% of energy charges.
  6. Fuel surcharge — variable charge based on fuel costs.
  7. Total bill — sum of all above.
Verify your meter reading against what the bill shows. Estimated readings (when the meter reader can't access) can lead to over-billing.

10 Practical Ways to Reduce Your Bill

  1. Set AC to 24°C, not 18°C. Every degree below 24°C increases consumption by 6–8%.
  2. Switch to LED lighting. LEDs use 80% less power than incandescent bulbs.
  3. Use a star-rated inverter AC. The upfront cost premium pays back in 1–2 summers.
  4. Run the washing machine full. Half-loads use almost the same energy as full loads.
  5. Unplug devices not in use. Standby power (TV, chargers, set-top box) can consume 5–10% of your total bill.
  6. Use a timer for the geyser. 15 minutes is usually enough — don't leave it on for hours.
  7. Clean AC filters monthly. Dirty filters make the compressor work harder, consuming 10–15% more power.
  8. Replace old refrigerators. A 15-year-old fridge can cost you ₹1,000+/month in wasted electricity.
  9. Use natural ventilation when possible. A ceiling fan at 75W replaces a 1,200W AC for 8+ months of the year in most of India.
  10. Consider solar panels. A 3 kW rooftop system can offset ₹2,000–3,000/month in bills and pays for itself in 4–5 years with government subsidies.

Why is my bill higher in summer even without AC?

Refrigerators work harder in summer (ambient temperature increases compressor cycles). Fans run longer. Water coolers (if used) consume 150–200W. Even without AC, summer bills are typically 20–30% higher than winter.

How accurate is my electricity meter?

Digital meters are generally accurate within 2%. If you suspect an error, ask your distribution company for a meter test. You can also verify by turning off all appliances and checking if the meter still registers consumption (which would indicate a wiring fault or meter error).

Is it cheaper to run AC at night?

Some states offer time-of-day (ToD) tariffs with lower rates at night (typically 10 PM–6 AM). If your state has ToD pricing, yes — running AC at night is cheaper per unit. Otherwise, the rate is the same regardless of when you use it.

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