Which rate plan is cheaper for you?
Many US utilities offer several residential plans: a flat or tiered default, one or more time-of-use (TOU) plans, and often an EV plan. The utility publishes each plan’s prices, but not which is cheapest for you, because that depends on when you use electricity, not just how much.
In billing systems, a plan is a set of rules applied to a load profile: the same kWh under two plans gives two different bills. This comparator runs that calculation for every plan your utility offers and ranks them by annual cost.
How this calculator works
Step 1: build an hourly load profile
You enter your utility and your household’s monthly kWh without the EV (your yearly total ÷ 12; the default is your state’s average from EIA). If you charge an EV at home, you add its monthly kWh and the hour charging starts.
The comparator spreads your use across the year month by month following your state’s actual residential pattern (EIA use per customer by month), and across each weekday and weekend day hour by hour following the typical single-family home in your state from NREL’s ResStock load profiles, scaled to your total. The EV’s kWh are layered on top, drawn at 7.2 kW (a typical Level 2 home charger) from your charging start hour.
Step 2: price every hour under every plan
Nearly every plan’s prices are transcribed from the utility’s own current tariff and rider sheets, all per-kWh riders and supply charges included, and marked “Checked” with its date on the utility’s page; the few not yet checked come from the OpenEI Utility Rate Database (URDB). The hour-by-hour period calendar gives the price period for every hour of weekdays and weekends in each of the 12 months. Each hour of the profile is priced under each plan:
- Flat plans: every kWh at the same price.
- Tiered plans: tiers apply to the month’s total kWh, relative to the baseline allowance.
- TOU plans: each hour gets the price of its period (peak, off-peak, and sometimes shoulder or partial-peak), with weekday and weekend rules where the tariff has them.
- EV plans: the same, often with a super off-peak window.
Seasons follow the utility’s own months, not a fixed summer.
Step 3: add fixed charges and rank
Each plan’s fixed monthly charge is added for all twelve months (converted from a daily charge where the utility bills per day), and a minimum bill, where the plan has one, acts as a floor. The comparator sums the year and ranks plans from cheapest to most expensive, showing the difference against the first plan listed for your utility.
How TOU periods and seasons work
A TOU tariff divides the day into periods with different prices. Some utilities put the peak in the late afternoon and evening, for example 4–9 pm, when solar output is falling. Off-peak covers most other hours. Some plans add a shoulder period on either side of the peak, and EV plans may add a super off-peak window, often overnight, priced below the standard off-peak rate.
The spread between peak and off-peak is what matters. On some plans peak is only modestly higher; on others the gap is wide. It depends entirely on the plan, and each utility page on this site shows the exact price of every period. The wider the spread, the more your timing decides the outcome.
Seasons matter too. Some utilities charge more in summer, when air conditioning drives system peaks. A plan that looks cheap in April can be expensive in August if your AC runs through the evening.
Tiers and baseline allowances
Tiered plans give each customer a baseline quantity of kWh per month, often varying by climate zone, season, and whether the home heats with electricity. Use within the baseline is priced at the lower tier; use beyond it is priced higher. Some tariffs have two tiers, some more. The comparator uses the baseline recorded for the plan in URDB; where your allowance depends on a climate zone other than the one the plan names, your tiers may differ.
Tiers reward low total use regardless of timing. A small, efficient household can do very well on a tiered plan, while a large household, or any household adding an EV or heat pump, may find most of its new kWh priced at the upper tier. Some plans combine tiers and TOU. The comparator handles these by splitting the kWh in each period across the tiers in proportion to the month’s total, the convention URDB and NREL’s System Advisor Model use.
Fixed and basic charges
Nearly every plan carries a fixed monthly charge, sometimes called a customer charge or basic service charge. It does not depend on how much you use. Some plans also set a minimum bill, the least you pay in a month however little you use. Plans differ here: some EV or TOU plans have a higher fixed charge in exchange for lower energy prices, and some utilities add an extra fee for a second meter.
For low-use households, fixed charges can decide the comparison. A plan that saves 2 cents per kWh saves $6 a month at 300 kWh, which does not cover a fixed charge $10 a month higher.
Who wins and who loses when switching
Some general patterns, which your own numbers can overturn:
- Likely winners on TOU: households with most use outside the peak window, people home during the day in mild climates, and anyone who can put large loads on timers.
- Likely winners on EV plans: EV owners who charge overnight inside the super off-peak window, especially with significant monthly mileage.
- Likely losers on TOU: households with heavy evening use that cannot move, particularly with long summer AC runtimes inside the peak window.
- Tiered plans suit: low, steady users whose total stays near the baseline.
For some households the difference between plans is small; for others it is large. The dollar difference shown helps you judge whether switching is worth it, and whether the saving depends on habits you can sustain. Where a utility allows switching back within a trial period, testing is low-risk.
What the comparison leaves out
The comparator prices energy charges, seasonal differences, fixed charges, minimum bills, and the per-kWh riders and supply charges in the tariff (for the few plans not yet checked, those URDB lists). It does not include taxes or local franchise fees, and some of those scale with kWh. Where such a charge is the same per kWh or the same percentage of the bill on every plan, it raises the totals without changing the ranking. Also excluded are low-income discounts, holiday calendars and critical-peak events, net-metering credits for solar, and any one-time enrollment requirements. Plans with demand charges are left out, because they depend on your peak kW, which the calculator cannot know.
Getting a better answer with your own data
The hourly profile is your state’s typical single-family home, not yours. If you have a smart meter, you can do better. Many utilities provide interval data, typically in 15-minute or hourly increments, through a “Green Button” download in your online account. That file shows exactly when your household used electricity over the past year.
With it you can check what share of your use really falls inside a plan’s peak window, in summer and winter, and compare it with the typical home. If more of your use lands in the peak than the typical home’s, the comparator’s TOU results are optimistic for you; if less, they are conservative.
Frequently asked questions
Why doesn’t the annual total match my bills?
It excludes taxes and local fees, and it uses a typical home’s hourly profile rather than yours. It is built to rank plans fairly, not to reproduce a bill to the cent.
Is time-of-use always cheaper?
No. TOU rewards use outside the peak. If much of your consumption falls in the evening and cannot move, a flat or tiered plan can be cheaper.
Where do the tariff prices come from?
From each utility’s own current tariff and rider sheets, transcribed and marked “Checked” with a date; the few plans not yet checked come from the OpenEI Utility Rate Database. Each plan is cross-checked against what the utility actually billed residential customers per kWh in EIA Form 861 before it is shown. Tariffs change, so check the effective date shown for each plan on your utility’s page, which also links the tariff document.
Should I add my EV before comparing?
Yes, if you have one or plan to. At 920 miles a month (about 11,000 miles a year, the average per car in FHWA’s Highway Statistics) in a car rated 30 kWh per 100 miles, an EV adds 920 × 30 ÷ 100 = 276 kWh a month, and when you charge it can change which plan wins.