Slow Cooker Power Station Calculator

A slow cooker only draws 100 to 400 W, so it is easy to assume a small power station will run one. The wattage is not the problem — the runtime is. A slow cook is 4 to 10 hours, and a small load held for that long adds up to a large number of watt-hours.

At 250 W for 6 hours that is 1,500 Wh of raw energy, and after inverter losses and a reserve the recommended battery capacity is over 2,000 Wh — a large power station, driven entirely by the hours, not the watts. The continuous-output requirement stays at 250 W the whole time, which almost any unit clears.

So for a slow cooker, battery capacity is the binding constraint, not the inverter rating. That is the opposite of a kettle or a toaster oven, where a brief high draw makes continuous output the limit.

The energy side of this uses the same method as the main Power Station Size Calculator. Two specifications decide whether a power station can run a slow cooker, and they are independent:

• Battery capacity, in watt-hours (Wh), is the stored energy. For a slow cooker this is the number that matters: a low draw over many hours is well over a kilowatt-hour, often two or more.
• Continuous AC output, in watts (W), is how much power the inverter can deliver at once. A slow cooker's 100–400 W sits comfortably inside almost any power station's inverter, so this is rarely the limit.

The practical question is whether the battery lasts the whole cook. To check how long a given unit runs a steady low load, use the Power Station Runtime Calculator.

• Rating label. The plate on the base lists volts and watts, or amps (amps × volts = watts). Some labels give a single figure; others list Low and High separately.
• Manual or manufacturer spec. Look for “rated power”, “wattage”, or a table of watts per setting.
• Watt meter. Plug the cooker in and read the wattage while the element is actively heating — that active draw is what you enter, and what the inverter has to supply. A meter also shows the lower long-run average once cycling starts, which is useful for a separate energy estimate but is not the figure for this calculator.

Small 1.5–3 qt cookers are often 100–150 W; 4–6 qt models are commonly 200–300 W; large 7–8 qt cookers can reach 320–400  W on High. Do not assume a figure from the quart size — read the label and enter that number, for the setting you plan to use.

Energy use is the input watts multiplied by the hours it runs. The wattages are small, but the hours are long, so the totals land squarely in large-power-station territory. These figures are a planning ceiling — a cooker with heavy thermostat cycling may use less.

Slow cookers have Low, High, and usually Warm settings, but the relationship between the setting and the power draw is not fixed and differs by model:

• Some models run the same heater on every setting and just change how often the thermostat cycles it — so the peak watts are identical and the average differs.
• Others switch between a lower-wattage and a higher-wattage element for Low and High.
• Low and High mostly change how fast the food reaches a simmer; both hold roughly the same temperature once there, so a longer cook on Low is not always less total energy than a shorter cook on High.

Because of that, the calculator does not convert a setting into a wattage — there is no “Low = 50%” or “Warm = 25%”. Enter the active input watts at the setting you plan to use — the draw while the element is heating, read from a watt meter if you can, not a long-run cycling average — and otherwise the nameplate maximum as a conservative planning value.

Once the food is up to temperature, a slow cooker's element switches on and off to hold it there, so the average power over a long cook can be noticeably below the nameplate wattage. The peak draw while the element is on is still the full input wattage.

How much the average drops is not predictable — it depends on the model, the setting, how full the pot is, the starting temperature of the food, the room temperature, and how often the lid comes off. So this calculator uses full entered watts for the full entered hours as a safe planning estimate and does not apply a duty-cycle discount.

Cycling can pull the average energy use below that estimate, but do not replace the cooker's active or rated wattage with a long-run average in this calculator, because the same input is also used to size the required continuous AC output — and the inverter still has to supply the full heating draw whenever the element switches on.

For a tighter energy-only figure, measure the total watt-hours over a full cook cycle, or multiply a measured average wattage by the cook hours, and use that number for capacity planning on its own. Either way, verify the power station's continuous AC output against the cooker's full active or nameplate wattage separately. To see how a steady low draw pulls a battery down over many hours, use the Power Station Runtime Calculator, and for a multi-figure capacity estimate add the phases as rows in the main Power Station Size Calculator — then still check the continuous output against the full wattage yourself.

The calculator sizes the cook only. Many slow cookers drop to a Warm setting after the cook, or you leave them on Low to hold the food, and that can run for hours more. Its power draw is usually lower than the cook, but it varies by model, so it is left out of the main calculation rather than guessed.

The cook phase and the keep-warm phase usually draw different wattages, so add their energy separately — never as one combined watts × hours. Work out cook energy (cook watts × cook hours) and keep-warm energy (keep-warm watts × keep-warm hours), then add the two watt-hour figures. For example, 250 W for 6 hours is 1,500 Wh, an 80 W warm setting for 3 hours is 240 Wh, and the total raw energy is 1,740 Wh. The 80 W here is only an illustration — use your own model's figure. If the maker publishes a single measured figure for a full cook-plus-warm cycle, use that instead.

To model both phases at once, add them as two rows in the main Power Station Size Calculator — one “Slow cooker — cook” device at the cook watts and hours, and a separate “Slow cooker — keep warm” device at the warm watts and hours. It calculates each phase separately and adds their watt-hours correctly.

Only for a short cook, or a very small cooker. A 500 Wh unit has roughly 325–400 Wh usable. A 150 W mini cooker for 2 hours is about 300 Wh raw, which just fits; a 250 W cooker for a full 6-hour braise is 1,500 Wh raw and far beyond a 500 Wh unit.

Output is never the issue — a 500 Wh power station's inverter handles a slow cooker's wattage easily. It is purely a capacity question: a slow cook is a multi-kilowatt-hour job, and a 500 Wh unit does not have the hours in it.

For a shorter cook, yes. A 1,000 Wh unit has about 650–800 Wh usable. A 200 W cooker for 3 hours is 600 Wh raw, roughly 880 Wh recommended — near the edge of a 1,000 Wh unit. A 250 W cooker for 6 hours (1,500 Wh raw, over 2,000 Wh recommended) does not fit.

As always with a slow cooker, the inverter is not the limit — a 1,000 Wh power station has far more continuous output than the cooker needs. Match the unit's usable capacity to your cook energy plus any keep-warm time. If you also want to keep a fridge, lights, or a router going during an outage, add them together in the Home Power Outage Calculator.

This is the practical range for a full slow cook. A 2,000 Wh unit has roughly 1,300–1,600 Wh usable — enough for a 200 W cooker over 6–8 hours, or a 250 W cooker for around 5 hours, with a little left for a short warm hold.

A 250 W cooker for a full 6-hour cook works out to roughly 2,206 Wh recommended, which is just past a 2,000 Wh unit's usable capacity — so a longer or higher-wattage cook, or a meaningful keep-warm period, points to a 3,000 Wh-class unit, ideally one with expandable batteries. Output is never the constraint; plan on capacity and recharge speed.

• Camping. A slow cooker is appealing off-grid — set it in the morning, eat in the evening — but the all-day runtime makes it one of the largest energy loads a campsite kitchen can have. Size the battery for the full cook. The Camping Power Station Calculator sizes the rest of your setup.
• RV. The inverter will not blink at a slow cooker's wattage; the question is whether the house battery bank has a couple of kilowatt-hours to spare over the day. The RV Power Station Calculator covers 12V and AC loads together.

A rice cooker runs the same low-and-slow way but finishes in under an hour. A toaster oven, an air fryer, and an induction cooktop are the opposite trade — high wattage, short runtime, and output-limited rather than capacity-limited.

A slow cooker is a low-stress way to cook during an outage — it needs no attention and its wattage is trivial for any power station. The catch is the total energy: a full cook is one to two kilowatt-hours or more, which is a large share of a portable unit's capacity.

For an outage, that usually means:

• Back up essentials first — medical equipment, the refrigerator, lighting, communication — and size those with the Home Power Outage Calculator.
• Check the cook energy against what you can spare after the essentials, not against the inverter rating.
• A shorter cook on High, or switching off the Warm setting once the food is done, saves a meaningful chunk of battery.

Check every item against your slow cooker and your situation before buying:

• Actual slow cooker input watts from the rating label or a watt meter — not a guess from the quart size.
• Intended setting — Low, High, or Warm — and the input watts at that setting.
• Continuous AC output (W) at or above the cooker's input watts. An easy bar for almost any power station.
• Battery capacity (Wh) at least the recommended figure from the calculator — the number that actually decides this.
• Expected cook duration in hours for the meals you make.
• Keep-warm duration — how long you hold the food after the cook.
• Keep-warm watts, if the manufacturer or a watt meter gives you one, for the extra-energy estimate.
• AC voltage matches the cooker (most countertop models are 120V; confirm yours).
• Outlet compatibility an AC outlet the plug fits, on a pure sine wave inverter.
• Recharge time from wall, vehicle, or solar, so the unit is ready for the next cook.

For a slow cooker, a power station in the right range is mostly a question of usable watt-hours. Confirm the unit's real usable capacity covers your cook energy plus any keep-warm hold, with a margin.