How Electricity Slab System Works in Pakistan
Pakistan’s electricity tariff is a progressive slab system: the first units cheap, each successive block costlier, and a single month above a threshold repricing everything. Understanding the slabs turns the bill from an invoice into a number you can forecast and influence. This page explains the structure, the key thresholds, and the calculation that answers "what will one more AC month actually cost me?"
How do slabs work in one paragraph?
Your monthly units fall into price blocks: the first 50 or 100 units price at the cheapest per-unit rate, the next block at a higher rate, and so on. You pay each block’s rate for the units within it — not the highest rate on all units. A month at 310 units pays the 0–100 rate on the first hundred, the 101–200 rate on the next hundred, and the 201–300 rate on the next hundred, plus one unit at the 301+ rate.
What happens to my bill if I cross 200 units?
The 200-unit line is a threshold, not a cliff: you pay the higher slab only on the units above each boundary, not retroactively on all units. What matters more is the protected/non-protected fork: staying at or under 200 units for six consecutive months earns protected-consumer status with lower base rates — explained in our protected-consumer guide. Cross it once and the clock resets.
Why does the same extra 100 units cost so much more some months?
Two mechanisms compound: each hundred units enters a higher slab, and the adjustment lines (FPA and QTA — each covered separately) multiply by the larger unit count. The bill calculator isolates each effect; what feels like a doubling for a modest usage increase is usually slabs plus adjustments landing together.
The slab structure, built from first principles
The tariff serves two goals simultaneously: affordable basic supply (the cheap low slabs) and progressive pricing for heavier consumption. The structure works marginally — each additional unit beyond a threshold prices at that threshold’s rate, not retroactively on all units — which is the source of most bill-argument confusion. The household that crosses 201 units doesn’t pay the 201–300 rate on the first 200; it pays that rate on unit 201 only. The cliff people fear is arithmetic, not policy.
The thresholds that matter most
The 200-unit boundary is the most consequential: it gates the protected-consumer status and separates the tariff’s subsidy intent from its cost-recovery tier. Below it: the government’s social pricing. Above it: commercial reality, and with it every slab’s FPA and QTA multiplication at full weight. Managing toward under-200 is a real financial discipline for households near the boundary — the bill calculator shows the annual saving from one appliance swap or habit that holds the number at 195 rather than 215.
Forecasting and managing the month
The practical use of slab literacy is forward-pricing the month before it ends: read the meter, subtract the opening reading, run the units through the calculator, compare against last month’s. A month tracking toward 350 units in week two leaves two weeks to adjust — the AC setpoint, the geyser timer, the office air-cooler days — and price the adjustment in units-saved rather than rupees, which is the unit the slab table actually speaks. The appliance cost tool prices each load’s monthly contribution to the total so the two-week correction finds its target precisely.
More questions answered
NEPRA revises rates periodically and the Finance Act can adjust them annually; rates cited as exact figures anywhere online date quickly. The bill itself prints the rate applied per slab, and the calculator uses current rates — which is the reliable reference for forward projections rather than any static table.
Not for domestic consumers — the slab structure is universal. Commercial and industrial tariffs simplify toward flat per-unit rates (with fixed demand charges instead), which is partly why businesses prefer predictability over the slab game; the bill anatomy covers commercial lines separately.
What matters is kW and hours — a 1.5-ton split inverter at 900W running 8 hours a day uses about 216 kWh monthly, landing in the upper-mid slabs. The AC cost tool prices both unit types with actual efficiency ratings and your usage hours, which beats any comparison table.
Two forces: AC load adds units, and those units fall in the higher slabs. A household at 150 winter units and 380 summer units doesn’t just pay 2.5× more — it pays the low-slab rate in winter and the punishing upper rate in summer, plus the adjustment lines scaling with the larger base. The seasonal gap is multiplicative, not additive.
Only partially — the bill is monthly and the slab resets each month. Load shifting within a month helps (running the geyser off-peak, staggering heavy appliances), but the season’s cooling load is largely inelastic. The durable lever is the solar transition that removes daytime AC units from the grid bill entirely.