Ever stared at your TNEB current bill and felt completely lost? You see “Units” on one side, a “Total Amount” on the other… but if someone asks, “So, how much does one unit of current actually cost?” most of us don’t have a clear answer.
Don’t worry, you are not alone! The honest truth is, there is no single fixed price for “1 Unit” in Tamil Nadu.
The price changes depending on who you are (a home, a shop, or a factory) and, more importantly, how much electricity you consume. Below, I’ve broken down exactly how the pricing works under the new tariff rules that came into effect on July 1, 2025.
1. Electricity Price Per Unit for Homes (Domestic)
This is the most common question. For domestic connections (Tariff LT I-A), the price per unit isn’t fixed; it changes based on the total units you consume every two months.
Simply put: “The more electricity you use, the higher the price you pay for every single unit.”
Real-World Examples
You live in a compact home, using just fans and lights. Your bi-monthly bill is around 80 units.
Your Price Per Unit: ₹0 (Free)
Reason: The first 100 units are absolutely free for everyone!
You have a TV, Fridge, and Mixie running. Your bill comes to about 400 units.
Your Price Per Unit: There isn’t one flat rate. The first 100 are free, and the rest are charged at a subsidized rate.
You install an AC or a Geyser. Suddenly, your usage jumps from 400 to 600 units.
- This is where it hurts! The “100 Free Units” offer is cancelled.
- You have to pay the highest slab price for all units consumed.
- For every unit that goes above 500, the price is: ₹8.40 / Unit
The Takeaway: If adding that extra AC pushes you into the High Slab, your bill will skyrocket. Trying to stay under 500 units is the best way to save money.
2. Electricity Price for Shops (Commercial)
For shops, offices, and commercial establishments (LT Tariff V), the calculation is slightly different. Here, “500 Units” is the magic number.
- Small Shops (Below 500 Units): You continue paying the old rates. No price hike for you.
- Big Establishments (Above 500 Units): You will have to pay the new, hiked rates.
No price hike. Price per unit: ₹10.15
Price hike applies. Price per unit: ₹10.45
Note: You also have to pay separate ‘Fixed Charges’.
3. Electricity Price for Industries
Industries are generally split into two categories:
- Small Industries (LT IIIB): If your load is under 50 kW, you continue with the old rate of ₹8.00.
- Large Industries (HT): These industries must pay the 3.16% hike. The new price is ₹7.50 (previously ₹7.25).
Note: For factories, “Demand Charges” and “Peak Hour Charges” (25% extra) significantly increase the final bill amount.
Quick Summary Table
Here is the approximate cost per unit as of July 2025:
| User Category | Price Per Unit (Approx.) |
|---|---|
| Home (Domestic) | ₹0 to ₹11.55 (Based on slabs) |
| Small Shop (<500 Units) | ₹10.15 (Unchanged) |
| Big Shop (>500 Units) | ₹10.45 (Increased) |
| Small Industry (<50 kW) | ₹8.00 (Unchanged) |
| Large Industry (HT) | ₹7.50 (Increased) |
Want to know exactly how much your next bill will be?
Click here to use the TNEB Bill Calculator 👉Frequently Asked Questions (FAQ)
Q: Did home electricity bills go up in 2026?
Answer: No! While it’s true that the regulatory body (TNERC) approved a 3.16% hike due to inflation, the Tamil Nadu government paid that difference on behalf of the people. So, for domestic users, the old rates continue for the 2025-26 period.
Q: Is there any chance for Commercial bills to go down?
Answer: If you run a small shop and keep your usage under 500 units bi-monthly, you will be charged the old (lower) rates. However, once you cross 500 units, the new hiked rates will apply to you.
Q: Is the “100 Units Free” scheme available for everyone?
Answer: This scheme is strictly for Home (Domestic) connections only. Shops and factories do not get 100 free units. Also, even for homes, if you consume a very high amount (e.g., over 1000 units), you might lose the subsidy benefits.
Check our other TNEB tools
TNEB Bill Calculator For Domestic