Sri Lanka electricity bill 2026: one extra unit can cost Rs 2,030

Sri Lanka's household electricity bill does not rise smoothly. Under the tariff the Public Utilities Commission (PUCSL) approved from 11 May 2026, the number of units you use in a month picks a band, and that band's rates apply to every unit on the bill. So a few units can move the whole bill.

The biggest jump is at 180 units. A 180-unit month costs Rs 6,420. A 181-unit month costs Rs 8,450. That one extra unit costs Rs 2,030.

What each usage level costs

Monthly bill for a 30-day cycle, fixed charge included.

Units in the month	Bill	Average per unit
30	Rs 230	Rs 7.67
60	Rs 630	Rs 10.50
90	Rs 1,840	Rs 20.44
120	Rs 3,280	Rs 27.33
150	Rs 5,100	Rs 34.00
180	Rs 6,420	Rs 35.67
200	Rs 10,350	Rs 51.75
250	Rs 15,350	Rs 61.40
300	Rs 20,350	Rs 67.83
400	Rs 30,350	Rs 75.88

Work out your own bill with the Sri Lanka electricity bill calculator.

Where the jumps are

Step	Bill before	Bill after	One unit costs
60 to 61 units	Rs 630	Rs 1,260	Rs 630
90 to 91 units	Rs 1,840	Rs 2,468	Rs 628
120 to 121 units	Rs 3,280	Rs 3,824	Rs 544
180 to 181 units	Rs 6,420	Rs 8,450	Rs 2,030

Two kinds of line cause them. At 60 and 180 units you move into a new band: every unit you had already used is re-priced at the new band's rates, and the fixed charge rises. At 180 units the fixed charge is Rs 1,500; at 181 it is Rs 2,500, and the first 180 units cost more too. At 90 and 120 units only the fixed charge steps up, from Rs 400 to Rs 1,000 and then to Rs 1,500.

Past 180 units the bill stops jumping and climbs steadily: every extra unit adds Rs 100. A 300-unit month is Rs 20,350.

What this means at home

• Check your meter before the cycle ends. If it is just under 60, 90, 120 or 180 units with days still to go, staying under the line saves far more than the few units you skip.
• A new appliance can cost more than its own units. If it pushes you past 180, the whole bill moves. The appliance running cost calculator prices that for your household.
• Big loads change the maths. Home EV charging takes most households past 180 on its own, which is why the EV charging cost calculator compares the standard tariff with time-of-use. The same top rate is what rooftop solar saves you, in the solar payback calculator.

How it is computed

The rule is short enough to write down. The month's total units pick a tier. Each tier has its own list of unit blocks with a rate per block, and its own fixed charge. Charge every unit at that tier's block rates, then add the fixed charge.

// Domestic tariff from 11 May 2026, 30-day cycle.
// A tier covers a range of monthly totals (0-30, 31-60, 61-90, 91-120,
// 121-180, 181+) and lists [blockEndUnit, ratePerUnit] pairs.
function bill(units: number, tiers: Tier[]): number {
  const tier = tiers.find((t) => units <= t.upTo) ?? tiers[tiers.length - 1];
  let energy = 0;
  let start = 0;
  for (const [end, rate] of tier.blocks) {
    const inBlock = Math.max(0, Math.min(units, end) - start);
    energy += inBlock * rate;
    start = end;
  }
  return energy + tier.fixed;
}

The figures above come from the engine behind the bill calculator, which matches PUCSL's own online calculator at every unit count from 0 to 2,000. They were last checked against the determination on 23 September 2026. For a billing cycle longer or shorter than 30 days, the unit limits scale with the number of days.

Sources

• PUCSL: Decision on Electricity Tariffs, May 2026 (PDF)
• PUCSL: end-user tariff decisions
• PUCSL: electricity bill calculator