Every time the bi-monthly electricity bill arrives, most of us just look at the total payable amount, pay it online, and forget about it. However, if you are trying to manage your monthly budget, understanding the actual 1 unit electricity cost in Tamil Nadu is essential. Knowing how your power consumption translates to rupees helps you make smart decisions about appliance usage, especially high-drain items like air conditioners.
The tariff structure set by the Tamil Nadu Electricity Board (TNEB) and regulated by TNERC is based on a telescopic slab system for domestic users and flat/slab models for commercial and industrial connections. Let’s explore exactly how much you are paying for electricity in Tamil Nadu in 2026, using the most up-to-date tariff data.
TNEB Domestic Electricity Bill Rate Per Unit 2026
If you have an LT-IA domestic connection for your home, your electricity charges per unit in Tamilnadu are calculated bi-monthly (once every two months). The Tamil Nadu government introduced a major policy update on May 10, 2026, which significantly altered the domestic electricity tariff by increasing the free electricity limit for low-consumption households.
Under the current system, residential users are divided into two main categories depending on whether their total consumption stays within 500 units or crosses it.
1. If Your Total Consumption is 500 Units or Less (Bi-Monthly)
For middle-class and lower-income families who manage to keep their overall consumption at 500 units or lower, the TNEB slab rate is highly supportive. Following the May 2026 upgrade, you are eligible for the 200 units free electricity in Tamilnadu scheme. This is a direct doubling of the previous 100-unit subsidy.
| Bi-Monthly Consumption Slab | Rate Per Unit (₹) | Slab Status |
|---|---|---|
| 0 – 200 Units | ₹0.00 (Free) | 100% Free |
| 201 – 400 Units | ₹4.95 / unit | Subsidized Rate |
| 401 – 500 Units | ₹6.65 / unit | Standard Domestic |
2. If Your Total Consumption is More Than 500 Units (Bi-Monthly)
If your consumption crosses 500 units even by a single unit, the tariff calculation changes. This is where the telescopic system is designed to charge higher consumers more. Once you cross 500 units, the 200-unit free subsidy is withdrawn, and you only receive 100 free units. The higher TNEB domestic rate slabs then apply to the remaining units.
| Bi-Monthly Consumption Slab | Rate Per Unit (₹) | Slab Status |
|---|---|---|
| 0 – 100 Units | ₹0.00 (Free) | 100% Free |
| 101 – 400 Units | ₹4.95 / unit | Subsidized Rate |
| 401 – 500 Units | ₹6.65 / unit | Standard Domestic |
| 501 – 600 Units | ₹8.80 / unit | Higher Tier |
| 601 – 800 Units | ₹9.95 / unit | Higher Tier |
| 801 – 1000 Units | ₹11.05 / unit | Premium Tier |
| Above 1000 Units | ₹12.15 / unit | Maximum Rate |
Real Bill Examples for Home Connections
To help you understand how to calculate electricity bill in Tamilnadu, let’s look at three practical bi-monthly consumption scenarios:
For a small household running basic lights, ceiling fans, and a television, the total usage stays well below the 500-unit threshold.
Calculation: 180 units are fully covered under the 200 free units slab.
Energy Charge: ₹0.00
Total Bill Amount: ₹0.00
For a typical family with a refrigerator, mixer-grinder, washing machine, and multiple fans, but no active air conditioner.
Calculation:
• First 200 units: Free = ₹0.00
• Next 150 units (201 to 350): 150 × ₹4.95 = ₹742.50
Energy Charge: ₹742.50
Total Bill Amount: ₹742.50 (No fixed charges apply for this tier)
For a home running a split AC during hot afternoons and nights, causing the bi-monthly consumption to cross 500 units.
Calculation:
• First 100 units: Free = ₹0.00
• Units 101 to 400 (300 units): 300 × ₹4.95 = ₹1,485.00
• Units 401 to 500 (100 units): 100 × ₹6.65 = ₹665.00
• Units 501 to 600 (100 units): 100 × ₹8.80 = ₹880.00
• Units 601 to 620 (20 units): 20 × ₹9.95 = ₹199.00
Energy Charge: ₹3,229.00
Total Bill Amount: ₹3,229.00 + minimal taxes
Other Residential & Subsidized Categories
Apart from standard homes, the Tamil Nadu Electricity Board supports several other residential and social categories with unique unit charges:
| Tariff Category | Target Users | Rate Per Unit & Details |
|---|---|---|
| LT-IB (Huts) | Thatched-roof homes and small huts in rural/urban areas | ₹0.00 (Fully Free) |
| LT-IA (Handloom) | Registered handloom weavers operating home looms | First 300 units free, subsequent units at standard domestic slabs |
| LT-IC & LT-ID | Bulk residential supply & Apartment common utilities (lifts, water pumps) | ₹8.80 / unit + fixed charge of ₹110 per kW |
| LT-IV (Agriculture) | Farmers and agricultural pump connections | ₹0.00 (Fully Free) |
Commercial Electricity Cost Per Unit in Tamilnadu (LT-V)
If you operate a shop, clinic, office space, private school, shopping mall, or any general business entity, your connection is categorized under LT Tariff V (Commercial / General Purpose). The commercial electricity bill rate is significantly higher than domestic rates and operates on a flat-slab system rather than a telescopic one.
| Bi-Monthly Consumption Slab | Rate Per Unit (Energy Charge) | Applicability |
|---|---|---|
| 0 – 100 Units | ₹6.65 / unit | Small kiosks, local tea stalls, empty shops |
| Above 100 Units | ₹10.45 / unit (applies to ALL units consumed) | Standard retail shops, offices, restaurants |
In addition to the per-unit energy charges, commercial consumers must pay additional overheads:
- Fixed Demand Charges: ₹110 per kW bi-monthly (for connected load ≤ 50 kW), or ₹332 per kW (for loads > 50 kW up to 112 kW)
- Electricity Tax (E-Tax): 5% of the total energy consumption charge
• Fixed Charges: 4 kW × ₹110 = ₹440.00
• Electricity Tax (5%): 5% of ₹3,135 = ₹156.75
• Total Estimated Bill: ₹3,731.75
Industrial Electricity Unit Charges in TN (LT-IIIB & HT-I)
TNEB industrial power tariff structures are designed to balance the needs of micro-entrepreneurs and large manufacturing plants. The tariff categories are broadly split into Low Tension (LT) and High Tension (HT) connections:
| Industrial Category | Tariff Code | Energy Rate Per Unit | Fixed / Demand Charge |
|---|---|---|---|
| Cottage & Micro Industries (Load ≤ 12 kW) | LT-IIIA1 | ₹4.95 (up to 500 units) / ₹7.15 (above 500 units) | ₹77 per kW bi-monthly |
| Power Looms | LT-IIIA2 | First 1,000 units FREE, subsequent units at ₹8.25/unit | ₹110 per kW bi-monthly |
| General Industries, IT Parks (LT) | LT-IIIB | ₹8.25 / unit | ₹84 to ₹165 per kW based on load limits |
| Large Industries, Factories (HT) | HT-I | ₹7.50 / unit | ₹589 per kVA per month |
| Private Educational Institutions & Hospitals (HT) | HT-IIB | ₹8.25 / unit | ₹589 per kVA per month |
| Temporary Supply / Construction Work | LT-VI / HT-V | ₹13.25 / unit | ₹608 per kW |
TNEB EV Charging Rate Per Unit (LT-VII & HT-VI)
To accelerate the adoption of electric vehicles, the Tamil Nadu government offers a dedicated tariff for public EV charging stations. The per-unit cost varies based on the time of day, encouraging charging during grid off-peak hours:
| Charging Time Window | Rate Per Unit (₹) |
|---|---|
| Peak Hours (6:00 AM – 9:00 AM & 6:00 PM – 10:00 PM) | ₹9.75 / unit |
| Normal Day Hours (9:00 AM – 4:00 PM) | ₹6.50 / unit |
| Off-Peak Night Hours (All other hours) | ₹8.10 / unit |
Master Reference: 1 Unit Electricity Cost in Tamil Nadu (Quick Look)
For a quick, bird’s-eye view, here is a consolidated master list of the cost per unit across the most common consumer segments in Tamil Nadu:
| Consumer Profile | Applicable Tariff | Actual Rate Per Unit (₹) |
|---|---|---|
| Home (Up to 200 units, when total ≤ 500) | LT-IA Domestic | ₹0.00 (Free) |
| Home (201 to 400 units, when total ≤ 500) | LT-IA Domestic | ₹4.95 |
| Home (401 to 500 units, when total ≤ 500) | LT-IA Domestic | ₹6.65 |
| Home (Up to 100 units, when total > 500) | LT-IA Domestic | ₹0.00 (Free) |
| Home (501 to 600 units) | LT-IA Domestic | ₹8.80 |
| Home (601 to 800 units) | LT-IA Domestic | ₹9.95 |
| Home (801 to 1000 units) | LT-IA Domestic | ₹11.05 |
| Home (Above 1000 units) | LT-IA Domestic | ₹12.15 |
| Rural Huts / Kutcha Houses | LT-IB Huts | ₹0.00 (Fully Free) |
| Agricultural Pump Sets | LT-IV Agriculture | ₹0.00 (Fully Free) |
| Very Small Kiosks (Up to 100 units) | LT-V Commercial | ₹6.65 |
| Standard Shop / Business (Above 100 units) | LT-V Commercial | ₹10.45 |
| Cottage Industries (Load ≤ 12 kW) | LT-IIIA1 Industrial | ₹4.95 / ₹7.15 |
| General LT Industry & IT Services | LT-IIIB Industrial | ₹8.25 |
| Large HT Factories & Heavy Industries | HT-I Industrial | ₹7.50 |
| Construction Sites & Temporary Connections | LT-VI Temporary | ₹13.25 |
Confused by Slabs? Let Our Smart Calculator Do the Work!
Calculating telescopic slabs, fixed demand charges, and electricity tax manually can be exhausting. Our automated tool handles everything in a fraction of a second. Enter your units and get a 100% accurate bill instantly.
Open TNEB Bill CalculatorWhat Exactly is 1 Unit of Electricity?
To put these numbers into perspective, it helps to understand what “1 unit” of electricity actually is. In technical terms, 1 unit equals 1 Kilowatt-Hour (kWh) of energy. This means that if you run a 1,000-watt appliance continuously for exactly one hour, you have consumed 1 unit of electricity.
To help you understand how everyday household appliances consume energy, here is a practical lookup table showing how long it takes for common devices to consume exactly 1 unit of electricity:
| Appliance | Average Power Wattage | Hours of Running to Consume 1 Unit |
|---|---|---|
| Smart LED Bulb | 9 Watts | 111 Hours |
| Super Efficient Ceiling Fan | 75 Watts | 13.3 Hours |
| Double Door Refrigerator (250 Liters) | 150 Watts | 6 to 7 Hours of compressor run time |
| Smart LED TV (43-inch) | 100 Watts | 10 Hours |
| Automatic Washing Machine | 500 Watts | 2 Hours |
| Inverter Air Conditioner (1.5 Ton) | 1,200 to 1,500 Watts | 40 to 50 Minutes |
| Water Heater / Geyser | 2,000 Watts | 30 Minutes |
Looking at the table, it is clear why split ACs and geysers are the primary reasons behind high electricity bills. Running a single 1.5-ton AC for 8 hours a day consumes approximately 8 to 10 units. Over a 60-day billing period, this single appliance adds 480 to 600 units to your total consumption, easily pushing your household into the more expensive non-telescopic slabs.
Why Does Tamil Nadu Use a Telescopic Slab System?
For most consumer goods, buying in bulk gets you a discount. With electricity in Tamil Nadu, however, the opposite holds true. The progressive telescopic slab system is built around the concept of social equity and conservation:
- Subsidizing Basic Needs: Low-consumption households (using basic fans and LED bulbs) are supported with free power and subsidized low-cost units to ensure basic electricity is affordable for everyone.
- Discouraging Overuse: High-income households with multiple luxury appliances (ACs, home theatres, water pumps) pay higher per-unit rates. This higher tier payment helps cross-subsidize the free units distributed to lower-income homes and agricultural sectors.
Frequently Asked Questions
Q. What is the cost of 1 unit of electricity in Tamil Nadu for home users?
For home users under the LT-IA tariff, the cost is telescopic. If your total bi-monthly consumption is under 500 units, the first 200 units cost ₹0.00 (free), units 201–400 cost ₹4.95 each, and units 401–500 cost ₹6.65 each. If your total consumption crosses 500 units, the first 100 units are free, units 101–400 cost ₹4.95, units 401–500 cost ₹6.65, units 501–600 cost ₹8.80, and further units cost up to ₹12.15.
Q. What is the TNEB domestic electricity bill rate per unit 2026?
The TNEB domestic electricity bill rate per unit in 2026 relies entirely on the May 10, 2026, policy upgrade. Households consuming ≤ 500 units enjoy the 200 free units limit, while those consuming > 500 units revert to the 100 free units limit. Rates per unit range from ₹0.00, ₹4.95, and ₹6.65 up to ₹12.15 depending on the specific slab your bi-monthly usage lands in.
Q. How to get 200 units free electricity in Tamilnadu?
To get the 200 units free electricity, your total bi-monthly consumption must be 500 units or less. If your consumption reaches 501 units, your free electricity limit is automatically reduced to 100 units, and the rest is billed at higher slabs. Keeping an eye on your consumption and adjusting high-power appliances can help you stay below this 500-unit limit.
Q. How much is the commercial electricity cost per unit in Tamilnadu?
Under commercial LT-V connection rules, the energy charge is ₹6.65 per unit if your total consumption stays under 100 units bi-monthly. If it crosses 100 units, you are charged a flat rate of ₹10.45 per unit for all units consumed. Additionally, fixed charges of ₹110 to ₹332 per kW are added bi-monthly alongside a 5% electricity tax.
Q. What are the industrial electricity unit charges in TN?
For micro and cottage industries (LT-IIIA1), charges are ₹4.95 per unit up to 500 units, and ₹7.15 per unit above 500. Standard LT industries (LT-IIIB) pay a flat rate of ₹8.25 per unit, whereas large HT factories (HT-I) pay ₹7.50 per unit plus a fixed demand charge of ₹589 per kVA monthly, with surcharges during peak hours.
Q. What is the TNEB EV charging rate per unit?
TNEB has introduced a time-of-day tariff for EV charging. During daytime normal hours (9:00 AM to 4:00 PM), the rate is ₹6.50 per unit. During peak hours (6:00 AM to 9:00 AM and 6:00 PM to 10:00 PM), it is ₹9.75 per unit. For all other off-peak hours (night and early morning), it is ₹8.10 per unit.
Q. How to calculate electricity bill in Tamilnadu manually?
To calculate your bill manually, check if your total units are under 500 or over 500. Under 500: Subtract 200 free units, multiply the next 200 units by ₹4.95, and any units above 400 up to 500 by ₹6.65. Over 500: Subtract 100 free units, multiply the next 300 units by ₹4.95, the next 100 units by ₹6.65, the next 100 units by ₹8.80, and so on. Add the sum of these segments to get your energy charge.