Time-of-use savings calculator

The lit round door of a washing machine mid-cycle, clothes tumbling behind the glass in a dark room. — Generated illustration — a depiction, not a photograph of a specific product.

The most anyone could save, on a 32¢/11¢ tariff

$1,772a year

8,438 kWh moved out of the peak window · nothing used less, only used later

That is every shiftable load below added together — an electric car, a pool pump and an electric water heater in one house, which few have. On the single most common one, an EV charge alone, the figure is $744. Rates of 32¢ and 11¢ are a common shape and nobody’s actual tariff; put yours in below.

Run it on your own rates

Two numbers decide this and neither is on your bill: the peak rate and the off-peak rate, both on your utility’s residential rate schedule. The third input is the honest one — how much of the load you will really move, as opposed to how much could theoretically move.

Your peak rate, ¢ per kWh

From your rate schedule, not your bill. The bill shows what you paid; the schedule shows the windows.

Your off-peak rate, ¢ per kWh

The overnight rate. Some utilities publish a super-off-peak that is lower again.

Kilowatt-hours a year you could move

The table below has a figure for each appliance worth moving. Add up the ones that apply to you.

How much of it you actually shift

100% — a timer shifts nearly all of a load; remembering to press a button shifts less.

Saved a year: $1,772
Over ten years: $17,720
Peak to off-peak: 2.9×
Moved off peak: 8,438 kWh

Moving 8,438 kWh from 32¢ to 11¢ saves $1,772 a year. That is the whole calculation: the kilowatt-hours you move, times the gap between the two rates. Nothing is used less — it is used at a different hour.

What is actually worth moving

The test is whether the load can move in time without anybody noticing. A car charging overnight passes completely; an oven at dinner time cannot move at all, because the point of it is the hour it happens in. Between those two lies everything with a timer.

Annual electricity from each appliance’s own page. The shiftable share is a stated assumption about how much of that load can realistically move — a tank on a timer moves most of itself, a dryer only moves as far as the household reschedules it.

Load	A year	Shiftable	Moved	Saved at 32¢ → 11¢
EV charging (Level 2 home)	3,541 kWh	100%	3,541 kWh	$744
Pool pump	2,160 kWh	100%	2,160 kWh	$454
Electric water heater	2,720 kWh	70%	1,904 kWh	$400
Electric clothes dryer	682 kWh	80%	546 kWh	$115
Dishwasher	244 kWh	90%	220 kWh	$46
Washing machine	97 kWh	70%	68 kWh	$14

EV charging (Level 2 home) dominates the list, and by enough that it changes the answer on its own: 3,541 kWh a year, all of it movable, worth $744 at these rates. If you charge a car at home, a time-of-use tariff is almost always worth having and a schedule is worth setting once. If you do not, the case rests on the water heater and the laundry, which is real but smaller.

What cannot move, and why that matters

Heating and cooling are the largest loads in most homes and they are the hardest to shift, because they run when the weather says so and the peak window is chosen to coincide with exactly that. Air conditioning peaks on a summer evening for the same reason the tariff does. Pre-cooling a well-insulated house before the peak window works, and pre-cooling a leaky one mostly heats the outdoors.

Cooking cannot move; the point of dinner is when it is. Lighting cannot move. A refrigerator runs continuously by definition. Together these are the reason a time-of-use tariff is not automatically cheaper: the peak rate applies to everything you could not reschedule, and if that is most of your usage you have simply bought a more expensive tariff for the hours you actually use electricity.

This is the honest test before switching: take a month’s usage, estimate what share falls inside the peak window today, and ask what share of that you would genuinely move. If the answer is “most of it” the tariff pays. If it is “some of it, when I remember”, compare the peak rate against your current flat rate before switching, because that is the rate you will be paying for everything you forget.

The part this site cannot compute for you

Every other figure on this site comes from a published dataset. This one cannot: there is no national database of residential time-of-use rate schedules, because they are set utility by utility and change on their own timetables. The defaults above are a common shape and explicitly nobody’s tariff, and the moment you type your own numbers in they stop mattering.

Two further things the calculation does not include. Many time-of-use tariffs have a different structure at weekends and in winter, so an annual saving computed from one weekday shape is approximate. And some utilities pair time-of-use energy rates with a demand charge based on your single highest fifteen-minute draw of the month, which rewards spreading loads out rather than merely moving them — running the dryer and the oven and the car charger at the same midnight hour can cost more than staggering them, even though every kilowatt-hour is off-peak.

Questions

Is a time-of-use tariff worth switching to?

It depends on one thing: how much of your usage you can actually move. If you charge a car at home the answer is almost always yes, because that single load is 3,541 kWh a year and it moves completely. If you cannot move much — no car, no electric water heater, someone home all day running the air conditioning through the peak window — a time-of-use tariff can cost you more than a flat one, because the peak rate applies to usage you cannot reschedule. Run the numbers above with a realistic share rather than an optimistic one.

Where do I find my peak and off-peak rates?

On the rate schedule, not the bill. The bill tells you what you paid; the schedule names the windows and the price in each, and utilities publish it as a PDF. Search your utility name plus “residential rate schedule”. You are looking for three things: the peak price, the off-peak price, and the hours the peak window covers — which is usually somewhere between 3pm and 9pm on weekdays, and often does not apply at weekends at all.

Does shifting usage help the grid or just my bill?

Both, and the tariff exists because of the first. Peak demand is what determines how much generation and how many wires have to exist, and the plants that run only during peak hours are the oldest and least efficient on the system. A time-of-use rate is a utility paying you to flatten its peak. Whether it also lowers emissions depends on what is generating at each hour, which an annual average cannot tell you — see the note on marginal versus average rates on the carbon page.

What about a battery?

A home battery charged off-peak and discharged during peak does mechanically what a timer does behaviourally, without anyone remembering. Whether it pays is the same arithmetic as any other purchase: divide the installed cost by the annual saving above. At the spreads on most residential tariffs the payback tends to be long unless the battery is also doing something else you value, such as backup during outages.

The longer guide to time-of-use pricing explains what the windows are and why utilities offer them · How every figure here is computed

Source: U.S. Energy Information Administration, Electric Power Monthly, Table 5.6.A, June 2026. U.S. Government work, public domain.