Estimate your two-monthly Tamil Nadu (TNPDCL/TNEB) bill with the free units, subsidised slabs and the 500-unit rule.
Quick answer
Tamil Nadu bills domestic power every two months, and the slab rates you pay depend on your total. Up to 500 units in two months, the first units are free (200 under the Government order of May 2026, earlier 100), 201–400 cost ₹4.70 and 401–500 cost ₹6.30. Cross 500 units and only the first 100 stay free, while higher slabs of ₹8.40 to ₹11.55 apply.
Rates last checked 9 November 2026 against official tariff orders. Values marked "see your bill" change month to month.
| Item | How it is worked out | Amount |
|---|
Tamil Nadu domestic slab rates
| Units per two months | Rate per unit |
|---|---|
| 1–200 | Free |
| 201–400 | ₹4.70 |
| 401–500 | ₹6.30 |
The 500-unit cliff
Because the whole slab table changes once two-month use crosses 500 units, the 501st unit can add far more than one unit's cost. Try 500 and 510 units in the calculator to see it. Keeping use at or under 500 units per billing cycle saves the most.
How to use this calculator
- Enter the units from your bill (current reading minus previous reading).
- Copy any monthly surcharge percentage from your latest bill. It changes every month.
- The result is an estimate. Meter rent, arrears, late fees, rebates and rounding are not included.
Want to know which appliance uses the most? Try the Appliance Electricity Cost Calculator and the AC Electricity Cost Calculator.
Compare every state in one place with our Electricity Bill Calculator. Other states: Delhi · Maharashtra · Uttar Pradesh · Karnataka · West Bengal · Telangana · Odisha · Jharkhand · Chhattisgarh · Gujarat · Rajasthan · Madhya Pradesh · Haryana · Punjab · Kerala · Bihar · Andhra Pradesh · Sikkim · Nagaland · Manipur · Mizoram · Uttarakhand · Himachal Pradesh · Jammu and Kashmir · Ladakh · Assam · Meghalaya · Tripura · Arunachal Pradesh · Goa · Chandigarh · Puducherry · Andaman and Nicobar Islands · Lakshadweep · Dadra and Nagar Haveli and Daman and Diu · Mumbai (Adani Electricity) · Mumbai (Tata Power) · Mumbai (BEST) · Torrent Power Ahmedabad · Torrent Power Surat · Kolkata (CESC)
Official sources
This calculator is built from official tariff orders and does not rely on third-party wording.