MDI and fixed charge calculator

On a Time-of-Use bill the fixed charge depends on your maximum demand, not just your units. Enter the four figures from your bill and see how the charge is built, and what bringing the peak down would save.

5 kW or more. Half of this is the floor for the fixed charge: 3.5 kW here.

Maximum demand indicator, printed on a ToU bill. The highest average load you drew in any half-hour.

Estimated bill before taxesRs 26,211600 units · fixed charge on 4.5 kW (your MDI)
Peak units (120 at Rs 46.85/unit)Rs 5,622
Off-peak units (480 at Rs 34.53/unit)Rs 16,574
Fixed charge (Rs 675/kW on 4.5 kW, the higher of half your load and your MDI)Rs 3,038
Fuel cost adjustmentRs 665
Quarterly adjustmentRs 312

Your MDI is above half your sanctioned load, so it sets the fixed charge. Bringing the peak draw down to 3.5 kW would cut it to Rs 2,363.

Domestic Time-of-Use rates from S.R.O. 279(I)/2026: Rs 46.85 peak, Rs 34.53 off-peak, Rs 675 per kW fixed. Commercial and industrial tariffs have their own MDI rules and rates and are not covered here. Taxes are added on the real bill.

How a Time-of-Use domestic bill is built

  1. Peak units at Rs 46.85 per unit, during the evening peak hours your DISCO publishes.
  2. Off-peak units at Rs 34.53 per unit, the rest of the day.
  3. Fixed charge at Rs 675 per kW on the higher of half your sanctioned load and your MDI.
  4. Adjustments: this month's fuel and quarterly figures on every unit, see this month's adjustments.
  5. Taxes on the real bill: GST, electricity duty, the PTV fee and income tax where it applies.

Our guide what MDI and fixed charges are explains the meter reading itself, and peak hours and Time-of-Use billing covers when the peak rate applies. Below 5 kW there is no MDI; use the bill calculator.

Frequently asked questions

What does MDI mean on an electricity bill?
Maximum Demand Indicator: the highest average load, in kilowatts, that your meter recorded over any half-hour in the billing month. It measures how hard you drew on the network at your busiest moment, not how many units you used.
How is the fixed charge calculated from MDI?
For a domestic Time-of-Use consumer the fixed charge is Rs 675 per kilowatt per month on the higher of two figures: half your sanctioned load, or your recorded MDI. So a 7 kW connection pays on at least 3.5 kW, and on more if the MDI was higher.
Who has a Time-of-Use meter?
Any residential connection with a sanctioned load of 5 kW or above must be given ToU metering and billed on tariff A-1(b). Units are charged at a peak rate during the evening peak hours and an off-peak rate the rest of the day.
Can I reduce my MDI?
Yes, by not running the biggest loads at the same time. Two air-conditioners, a water pump and an iron starting together set a high half-hour demand that then fixes the charge for the whole month. Staggering them lowers the MDI without using fewer units.
Do commercial connections use the same figures?
No. Commercial and industrial tariffs have their own MDI rules and their own rates. This calculator is for domestic Time-of-Use connections only.