Your neighbour uses roughly the same appliances as you, yet their bill is half of yours. The reason usually is not theft or a faulty meter — it is slab tariffs. A reliable electricity bill calculator India 2026 reveals the hidden logic: the more units you consume, the more each additional unit costs, because India prices power on progressive slabs set by each state’s regulator.

This guide breaks down exactly how your bill is built — energy charges, fixed charges, Fuel Adjustment Charge, and electricity duty — with state-wise 2026 rates and three worked examples. Use CalcDesk’s free Electricity Bill Calculator to compute yours, and browse the India Life calculator hub for every home-energy tool.

What Makes Up Your Electricity Bill

An electricity bill in India is never just “units × rate”. It is regulated pricing set by each state’s State Electricity Regulatory Commission (SERC) — DERC in Delhi, MERC in Maharashtra, KERC in Karnataka, TNERC in Tamil Nadu. The distribution company (discom) files a tariff petition, the SERC holds hearings, and the approved rates become your bill.

A common misconception is that electricity has one national price. In reality, tariffs differ sharply between states and even between discoms in the same state. Your bill has four main parts: energy charges (units × slab rate), a fixed charge based on sanctioned load, the Fuel Adjustment Charge (FAC) that moves monthly, and electricity duty levied by the state.

The Electricity Bill Formula

The critical idea is the Σ (summation) across slabs: you do not pay your top rate on every unit. If your state charges ₹3 for the first 100 units and ₹6.50 above 400, a 450-unit household pays the low rate on the first block and the high rate only on the units above each threshold. To attribute the bill to individual devices, use the Appliance Electricity Cost Calculator.

Table 1 — State-wise Domestic Slab Rates (2026)

Indicative domestic tariffs for major discoms. Rates exclude fixed charges, FAC and duty.

Table 2 — Sample Monthly Bill: Delhi vs Maharashtra

Energy charge only, using the slab rates above (fixed charge, FAC and duty extra).

The gap looks dramatic because Maharashtra’s higher slabs bite hard above 100 units — a reminder that the same consumption costs wildly different amounts by state. (Real Maharashtra bills soften via a Tariff subsidy for lower slabs; figures here isolate the slab arithmetic.)

Worked Example 1 — Delhi Household, 180 Units/Month

Worked Example 2 — Maharashtra Home, 350 Units with Summer AC

Worked Example 3 — Karnataka Commercial Connection, 800 Units

Fixed Charges and Sanctioned Load Explained

One part of your bill has nothing to do with how many units you use: the fixed charge, levied on your sanctioned load (measured in kW or kVA). When you take a connection, you declare a load — say 3 kW for a small flat or 5–8 kW for a larger home with AC. The discom charges a monthly fixed amount per kW of that sanctioned load, typically ₹50–250 in total, to cover the cost of keeping capacity available for you whether you use it or not.

This is why a locked second home still receives a bill, and why over-declaring your load quietly inflates every month’s fixed charge. Many households sanction far more load than they need “to be safe”, then pay for it for years. If your actual peak usage is well below your sanctioned load, applying to reduce the load can shave the fixed component. Conversely, running heavy appliances beyond your sanctioned load can attract penalties or a forced load enhancement, so the right approach is to match sanctioned load to your genuine peak demand.

Time-of-Day Tariffs — The 2026 Shift

A growing number of Indian discoms are rolling out Time-of-Day (ToD) or Time-of-Use tariffs for domestic consumers, following central guidelines. Under ToD, the per-unit rate changes with the hour: power is cheaper during solar-rich daytime hours and costlier during the evening peak. The logic is to shift flexible loads — washing machines, water pumps, EV charging, even pre-cooling with AC — into low-tariff windows, easing grid stress and rewarding you with a lower bill.

For households, ToD is an opportunity. Running your heaviest appliances at off-peak times can cut the effective rate on those units by 15–20%. If you also have rooftop solar, self-consuming during the cheap daytime window and avoiding grid draw in the expensive evening peak amplifies the saving. As smart meters spread across India in 2026, ToD billing will become more common, so understanding your discom’s peak and off-peak hours is fast becoming as important as knowing your slab rates.

Common Electricity Bill Mistakes

• Assuming a flat per-unit rate. People multiply total units by one number and get confused by the actual bill. Your marginal unit costs far more than your average — always think in slabs.
• Ignoring fixed charges on low usage. If you use very few units, the fixed charge and minimum charge can dominate the bill — a locked second home still gets billed.
• Blaming FAC surprises on errors. A bill that jumps ₹200 month-on-month is often just FAC moving with fuel costs, not a mistake.
• Sizing appliances by price, not running cost. A cheap 3-star AC pushes hundreds of units into the top slab every summer, costing far more over its life than a 5-star unit.
• Never reading the slab break-up. The bill shows exactly how many units fall in each slab — ignoring it means missing where the money actually goes.

Tips to Lower Your Electricity Bill

• Target the top slab. Cutting the last 100 units of a heavy bill saves more than cutting the first 100 — focus efficiency where the rate is highest.
• Upgrade the biggest loads first: AC and refrigerator. A 5-star BEE AC can save ₹6,000–9,000 a year over a 3-star — see the AC running cost guide.
• Consider rooftop solar. With the PM Surya Ghar subsidy, a system pays back in 5–7 years and can zero out your grid bill — details in the solar ROI guide.
• Switch to LED lighting and set the AC to 24–26°C — each degree lower adds roughly 6% to AC consumption.
• Track monthly units to catch a phantom load, faulty appliance or meter issue before it inflates several bills.