Keep Above
Slow cooker or oven
A slow cooker draws little for many hours; an oven draws a lot for fewer. Which of those adds up to more depends entirely on the numbers, which is what this page does: each side's rated watts and minutes per cook, at your own price per kWh, landing on a cost per use, per week and per year. No winner is declared.
On the rating plate or label
On the rating plate or label
Put in your price per kWh from your power bill, then each side's rated power and how long one use runs. Nothing here is read from your budgets, and nothing is saved.
| Option A | Option B | |
|---|---|---|
| Rated power | — | — |
| Energy one use takes | — | — |
| Cost of one use | — | — |
| Cost a week | — | — |
| Energy a year | — | — |
| Cost a month | — | — |
| Cost a year | — | — |
Why can hours of low power match minutes of high power?
Energy is the draw multiplied by the time, so neither figure means anything on its own. A small draw held all afternoon and a large one held for an hour can land in much the same place, and which way it falls is decided entirely by the two pairs of numbers entered above. That is why each side is entered as what it actually is: the watts on the plate and the real length of the run, not a rounded idea of it.
Both sides here hold a temperature, so both spend part of the run coasting with the heat off — and the longer the run, the more of it is coasting. A pot that has reached temperature only has to replace what escapes through its walls and its lid; an oven settled at its setting is doing the same thing for a much larger space and a door that opens. Costing every minute at full rated power therefore overstates a long session by more than a short one, whichever appliance the long session belongs to.
This is one of the tools built into Keep Above
Keep Above is a budgeting app where you enter your bills and income and it works out the balance you need to keep — so you can see what's safe to spend. No bank connection, no ads on your data.
Running costs never arrive as a bill with a date on it; they show up inside the balance — budgeting apps with no bank connection sets out what each one asks you to keep entering.
About this calculator
How do I enter an eight-hour cook?
The minutes field runs to 600 — ten hours — so an all-day cook is entered as its real length, 480 minutes for eight hours. The comparison stays honest exactly because the long low-watt session and the short high-watt one are both entered as what they actually are.
Does the low setting draw less than the high one?
Where a plate gives one figure, it is the draw while the element is on, and a lower setting reaches its lower temperature by having the element on for less of the time. Some cookers state a figure for each setting; where they do, the setting this cook would actually use is the one whose watts belong in the rated-power field. Where they do not, the single figure is the ceiling and the run would sit under it.
Does either side really draw its rating for the whole cook?
Neither does. A slow cooker draws its plate figure while it is bringing the pot up and while it is topping the heat back up, and less of the time in between; an oven does the same thing on a larger scale once it reaches its setting. The columns here cost every minute at the plate figure, which makes both the upper end rather than a meter reading — and the longer the cook, the further that figure sits above what a meter would show.
Where is the wattage written on a slow cooker?
On the base, usually moulded or printed underneath, near where the cable enters. The oven's own plate sits on the frame the door closes against, or on the back of a freestanding one. Both give the figure in watts (W), or in kilowatts (kW) where 1 kW is 1 000 W. Your own bill is where the price per kWh comes from; this page has no default for it.
Why do both sides use the same number of cooks?
Because a use here is a meal cooked, and a pot of something is one meal whether it took eight hours or one. Holding the count still is what leaves the hours free to do all the work in this particular comparison. That is the whole shape of this page: the same number of cooks, very different lengths of cook.