Most electricity bills in India work the way you'd expect. Cross into a higher slab and only the extra units get charged at the higher rate. The first 50 stay at the first-slab price no matter how much you use.
Kerala's domestic tariff stops working that way at 250 units. Past that line KSEB switches to a non-telescopic slab, where the higher rate applies to every unit on the bill, including the ones you'd already been charged cheaply for.
The bill jumps 464 rupees for one extra unit. The next 49 units cost 377 rupees between them. Using 251 units costs more per unit than using 300.
Table of contents
- Telescopic and non-telescopic billing
- KSEB slab tables
- The bill at 251 units
- Cost of the crossing unit
- Smaller jumps at other boundaries
- What 250 units looks like in appliances
- Checking your meter mid-cycle
- FAQ
- Sources
Telescopic and non-telescopic billing
Telescopic means each band of units is billed at its own rate and only the excess moves up. Use 120 units and you pay the 1-50 rate on the first 50, the 51-100 rate on the next 50, and the 101-150 rate on the last 20.
Non-telescopic means one rate applies to your entire consumption, chosen by the band your total lands in. There is no cheap first 50. Every unit bills at the same price.
KSEB bills telescopically up to and including 250 units a month, and non-telescopic above that. That single switch produces the cliff.
KSEB slab tables
Telescopic, for monthly consumption up to 250 units:
| Units | Rate per unit |
|---|---|
| 1-50 | Rs 3.35 |
| 51-100 | Rs 4.25 |
| 101-150 | Rs 5.25 |
| 151-200 | Rs 6.60 |
| 201-250 | Rs 7.60 |
Non-telescopic, above 250 units, where the rate hits every unit:
| Monthly consumption | Rate on all units |
|---|---|
| 251-300 | Rs 7.00 |
| 301-350 | Rs 7.60 |
| 351-400 | Rs 8.00 |
| 401-500 | Rs 8.60 |
| Above 500 | Rs 9.30 |
The fixed charge for a single-phase domestic connection runs from Rs 40 at the lowest band to Rs 185 above 500 units, and it steps up at the same boundaries. Electricity duty for domestic consumers is 10% of the energy charge. Meter rent is extra and doesn't change with consumption.
Rs 7.00 in the 251-300 band is lower than the Rs 7.60 charged on units 201-250, which looks like relief. It isn't. Under telescopic billing only 50 units ever paid Rs 7.60. Under non-telescopic billing all 251 pay Rs 7.00.
The bill at 251 units
Energy charge plus fixed charge plus 10% duty, worked out at each end of the boundary:
| Units | Energy charge | Fixed | Duty | Total |
|---|---|---|---|---|
| 249 | Rs 1,344.90 | Rs 125 | Rs 134.49 | Rs 1,604.39 |
| 250 | Rs 1,352.50 | Rs 125 | Rs 135.25 | Rs 1,612.75 |
| 251 | Rs 1,757.00 | Rs 145 | Rs 175.70 | Rs 2,077.70 |
| 300 | Rs 2,100.00 | Rs 145 | Rs 210.00 | Rs 2,455.00 |
One unit takes the bill from Rs 1,612.75 to Rs 2,077.70. That's Rs 464.95 for a unit of power worth about Rs 7.
For comparison, the step from 249 to 250 costs Rs 8.36. Same meter, same house, one unit later, and the price of that unit is 56 times higher.
Cost of the crossing unit
Inside the 251-300 band, one more unit costs Rs 7.00 plus 10% duty, so Rs 7.70. The crossing unit costs Rs 464.95, which is 60 units of ordinary consumption at that rate.
- crossing from 250 to 251 units: Rs 464.95 for one unit
- going on from 251 to 300 units: Rs 377.30 for 49 units
The crossing unit costs 1.23 times what the following 49 cost combined. Almost all the damage happens at the boundary, so once you're over it you may as well use the rest of the band.
It also means cutting back saves less the further past 250 you are. Coming down from 255 units to 250 saves Rs 495.75, or Rs 99.15 for each unit you avoid. From 300 down to 250 saves Rs 842.25, a bigger total but only Rs 16.84 per unit of effort. If you're 5 units over, cutting those 5 is the best electricity saving a Kerala household can make. Once the meter reads 251 the money is spent, and cutting back afterwards returns Rs 16 to Rs 20 a unit instead of Rs 99.
The averages tell the same story. At 250 units the bill averages Rs 6.45 a unit. At 251 it averages Rs 8.28. At 300 it's back down to Rs 8.18, slightly cheaper per unit than 251.
Smaller jumps at other boundaries
Every non-telescopic boundary has a jump, because the whole-consumption rate steps up at each one:
| Boundary | Bill before | Bill after | Jump |
|---|---|---|---|
| 250 to 251 | Rs 1,612.75 | Rs 2,077.70 | Rs 464.95 |
| 300 to 301 | Rs 2,455.00 | Rs 2,666.36 | Rs 211.36 |
| 350 to 351 | Rs 3,076.00 | Rs 3,243.80 | Rs 167.80 |
| 400 to 401 | Rs 3,675.00 | Rs 3,958.46 | Rs 283.46 |
| 500 to 501 | Rs 4,895.00 | Rs 5,310.23 | Rs 415.23 |
The 250 boundary is the worst because it's the only one where the billing method itself changes. At 300 or 400 you're already non-telescopic and only the rate moves. At 250 you lose the cheap early bands entirely.
If your household normally lands between 240 and 260 units, watch that band. At 320 or 480 the cliff ahead is smaller, but the same logic applies: check where you are a week before the reading.
What 250 units looks like in appliances
Units per month is watts times hours times 30, divided by 1,000. A fridge never draws its nameplate wattage continuously, so it gets a load factor, the fraction of time the compressor actually runs.
| Appliance | Draw and use | Units per month |
|---|---|---|
| 1.5 ton AC, 3-star | 1,500 W, 4 h/day | 180.00 |
| 200 L fridge | 150 W, 24 h at 0.35 load | 37.80 |
| 2 kW geyser | 2,000 W, 30 min/day | 30.00 |
| Laptop | 65 W, 8 h/day | 15.60 |
| Washing machine | 500 W, 1 h/day | 15.00 |
| Ceiling fan | 60 W, 8 h/day | 14.40 |
| LED TV | 90 W, 5 h/day | 13.50 |
| 1 kW iron | 1,000 W, 20 min/day | 9.90 |
One AC running four hours a night is 180 units on its own. Add a fridge and you're at 218 before lights, fans or anything else. That's why the 250 line catches ordinary households in a Kerala summer, not just large ones.
Half an hour less AC per day is 22.5 units a month. If you're 5 units over the line, that one change saves Rs 495.75.
The appliance electricity cost calculator does this per device with the load factor included, and ranks which appliance eats the largest share of your bill.
Checking your meter mid-cycle
You can't act on this after the reading is taken. The check has to happen while the cycle is still running, and it needs your current meter reading rather than an old bill.
Take your reading around day 20 of a 30-day cycle and scale it up:
- 170 units by day 20 projects to 255. Over the line. You need to hold the last 10 days to 80 units, or 8 a day.
- 180 units by day 20 projects to 270. You need 70 units in 10 days, or 7 a day.
- 190 units by day 20 projects to 285. You need 60 units in 10 days, or 6 a day.
At 190 by day 20, 6 units a day is below what a house with an AC will manage. Stop trying and use the band you're already in. At 170 the target of 8 a day is reachable by cutting the geyser and an hour of AC, and it's worth about Rs 496. Half an hour less AC a day is usually the whole gap.
To get units consumed from two readings, the Indian electricity calculator takes the previous and current reading with a per-unit rate and gives you the consumption and total. Feed it your day-20 reading against the cycle's opening reading and you have the number this projection needs.
Two caveats. KSEB bills most domestic consumers on a two-month cycle, and the slab limits apply to the monthly average of that cycle, so a 500-unit bimonthly reading is treated as 250 a month. Households under 200 units for the cycle also get a state subsidy on both the fixed and energy charge, applied without a request.
FAQ
What is non-telescopic billing in KSEB?
It charges your entire monthly consumption at a single rate set by the band your total falls in. Above 250 units a month, domestic consumers in Kerala are billed this way, so the cheaper first-50 and first-100 rates no longer apply to any part of the bill. Most other Indian states bill telescopically, which is why calculators built on the general slab model get Kerala bills wrong.
How much does crossing 250 units cost?
Rs 464.95 on a single-phase domestic connection. The bill goes from Rs 1,612.75 at 250 units to Rs 2,077.70 at 251, which includes the fixed-charge step from Rs 125 to Rs 145 and 10% electricity duty.
Is 251 units more expensive per unit than 300 units?
Yes. At 251 units the bill averages Rs 8.28 a unit, and at 300 it averages Rs 8.18. Both sit in the same Rs 7.00 band with the same Rs 145 fixed charge, and spreading that charge over more units lowers the average. No consumption above 250 costs less than 250 units does, so dropping under the line is always cheaper if you can reach it.
Does the 250 limit apply to a two-month bill?
The limit is monthly. On a bimonthly cycle KSEB applies the slabs to the monthly average, so 500 units across two months is assessed as 250 a month.
Sources
- KSEB bill calculator tariff tables: LT-1A domestic telescopic and non-telescopic slab rates, single-phase fixed charges by band, and the 10% duty and bimonthly subsidy rules
- Kerala State Electricity Regulatory Commission: tariff orders for the FY 2023-24 to 2026-27 control period that set the domestic slab structure
- Bajaj Finserv KSEB tariff summary: corroborating telescopic slab rates from Rs 3.35 to Rs 7.60
- Service charges for new power connections in Kerala revised: 24 September 2026 revision to connection service charges, separate from the consumption tariff
- Every bill total, boundary jump, per-unit average and appliance unit figure in this article was computed from the slab rates above and checked against the ToolMintX electricity calculators
