Fixed vs variable rate calculator
An example. Use the price on the plan's label.
Zero for a flat price. Negative for a falling price.
Use the price from your bill if you know it.
Total cost over 12 months
If the variable price rises by less than the break-even amount each month, the variable plan is cheaper over this term.
A straight-line rise is a simple stand-in for a price that really moves up and down. The starting prices and the monthly rise shown are examples.
How the two plans are compared
- Fixed plan. Cost equals monthly kWh times the fixed price, times the number of months, plus any monthly fee.
- Variable plan. The price starts at its first-month level and changes by the monthly rise you enter. The calculator adds up each month's kWh times that month's price, plus any monthly fee.
- Break-even. The monthly rise at which the two totals are equal. If you expect a smaller rise, the variable plan is cheaper. If you expect a larger one, the fixed plan is.
A straight-line rise stands in for a real price that goes up and down. It is a simple way to ask how much of a rise you can tolerate.
A worked example
| Variable price rise each month | Variable price, month 12 | Variable plan | Fixed plan | Cheaper plan |
|---|---|---|---|---|
| 0.00 cents | 16.23 cents | $1,703 | $1,913 | Variable |
| 0.10 cents | 17.33 cents | $1,761 | $1,913 | Variable |
| 0.20 cents | 18.43 cents | $1,819 | $1,913 | Variable |
| 0.30 cents | 19.53 cents | $1,876 | $1,913 | Variable |
| 0.50 cents | 21.73 cents | $1,992 | $1,913 | Fixed |
Source: Use: 874 kWh a month, the 2025 US average from EIA Form EIA-861. Prices are built around the US average of 17.23 cents and are examples, not offers.
Where this choice exists
You can pick between fixed and variable plans only where you can choose a retail supplier, in a group of states and DC. In most of the country the utility sets one price. See the states where you can choose a supplier and fixed versus variable plans for how each works.
What to read in the plan before you decide
- The term, and what the plan renews into. Many fixed plans end in a variable price unless you act.
- Any early termination fee, and any fee that applies if you use too little or too much electricity.
- Whether the price includes delivery charges, or whether they are added.
- How a variable price is set and how much notice you get before it changes.
What the calculator leaves out
It treats your use as the same every month, and a real home uses more in summer or winter. It leaves out taxes, fees that depend on use and the price of switching again. If your plan is in Texas, the label for each plan lists prices at three usage levels, which helps with the usage point. See fixed versus variable in Texas.
Frequently asked questions
Is a fixed or a variable rate cheaper?
It depends on how the variable price moves. A variable plan often starts lower. A fixed plan wins if the variable price rises enough. The calculator shows how much it has to rise.
What is the break-even rise?
The monthly price increase at which a variable plan and a fixed plan cost the same over the term. A smaller rise favors the variable plan.
Can a fixed rate change?
In many places only for limited reasons, such as changes in delivery charges or government fees. Read the plan terms.
Does this tool store my plan details?
No. It runs in your browser and nothing you enter is sent to our servers.