Electricity Rate Analysis Calculator

It's a simple index the calculator assigns to whichever of the three bills comes out lowest: 1 means the flat-rate bill was cheapest, 2 means the time-of-use bill won, and 3 means the demand-charge bill won. It's a label for the winning scenario, not a measured quantity — the dollar amount you actually care about is shown separately in Flat Rate Bill, TOU Bill, or Demand Charge Bill.

Peak Usage % determines how your Monthly Usage is split between the higher TOU On-Peak Rate and the lower TOU Off-Peak Rate — the calculator multiplies your usage by that percentage to get peak kWh, applies the on-peak rate to that share and the off-peak rate to the remainder, then adds the fixed charge. Because the on-peak rate is typically much higher, shifting a larger percentage of usage into peak hours pushes the TOU Bill up, which is exactly why utilities design TOU rates to reward customers who shift usage to off-peak hours.

The calculator reuses the Flat Rate you entered for all of your energy usage in the demand-charge scenario, then adds Peak Demand times Demand Charge on top as the capacity fee — it doesn't ask for a separate, often-lower demand-tariff energy rate the way many real commercial rate sheets do. That makes the Demand Charge Bill a useful illustration of how demand charges add to a bill, but you should substitute your actual tariff's energy rate before treating the comparison as a precise dollar figure.

Annual Savings vs Worst is calculated as the difference between the most expensive of the three bills and the cheapest, multiplied by 12 — it compares the best option against the single worst option, not against whichever rate you're currently paying. If you're currently on, say, the TOU rate and it isn't the most expensive of the three, your real-world annual savings from switching to the cheapest option would be smaller than this figure, which always assumes you're starting from the worst case.