Converting Between the Oven, the Slow Cooker and the Pressure Cooker
The three appliances cook the same food by three different mechanisms, which is why the conversion factors are not simple divisions. A domestic oven runs at 180 °C and drives moisture off the surface, so a stew thickens as it cooks. A slow cooker runs at roughly 93 °C on LOW and traps the steam, so nothing reduces and nothing browns. A pressure cooker runs at about 121 °C and finishes the job far faster, but only because it never lets the steam escape.
The calculator converts in both directions, but conversion is only safe for some dishes. A braise or a stew moves between all three appliances cleanly. A crisp-skinned roast chicken does not move anywhere, and no arithmetic will fix that. Read the safety section below before you convert anything.
What LOW, HIGH and WARM Actually Mean
Slow cooker settings are temperatures, not power levels, and they are lower than most people assume. Manufacturer manuals and test-kitchen measurements typically put LOW at around 93 °C, HIGH at around 149 °C, and WARM at around 70 °C. Exact figures vary between brands and with how full the pot is, so treat them as ranges. Crucially, LOW and HIGH reach the same final temperature for the food; HIGH simply gets there faster, which is why HIGH for three hours and LOW for seven can end up almost identical.
| Setting | Typical Temperature | What It Is For |
|---|---|---|
| WARM | About 70 °C | Holding cooked food for serving; not a cooking setting |
| LOW | About 93 °C | All-day cooking; gentle, forgiving, best for tough cuts |
| HIGH | About 149 °C | Faster cooking; reaches temperature sooner, same finish |
Converting between the two settings is a rule of thumb rather than an equation: one hour on HIGH is roughly two to two and a half hours on LOW. Use the low end of that (two hours) for dense, heavy dishes such as a large piece of shoulder, and the high end for something looser such as a chilli or a soup.
Converting from the Oven
These figures apply to braises and stews, which is what most oven-to-slow-cooker conversions actually are. They assume the liquid has already been reduced by roughly half to account for the slow cooker's trapped steam, which is covered in the safety section. They also assume you have browned the meat first on the hob, because a slow cooker will not do it for you.
A pressure cooker at high pressure runs at about 15 psi, which raises the boiling point of water to roughly 121 °C. That is nearly 30 °C above a slow cooker on LOW, which is why the times collapse so dramatically. The pressure cooker column below does not include the time to come to pressure or the natural release, and both matter: a large, full pot can take 10–15 minutes to reach pressure, and a natural release can add another 10–20. Add both when you plan, or the dish will be late.
| Oven at 180 °C | Slow Cooker LOW | Slow Cooker HIGH | Pressure Cooker |
|---|---|---|---|
| 30 minutes | 4–6 hours | 2–3 hours | 15–20 minutes |
| 1 hour | 6–8 hours | 3–4 hours | 25–30 minutes |
| 2 hours | 8–10 hours | 4–6 hours | 30–40 minutes |
Food Safety: The Rules That Are Not Flexible
Liquid. A slow cooker traps steam, so almost none of the liquid you put in ever leaves. An oven recipe at 180 °C for two hours may lose half its liquid to evaporation; the same recipe in a slow cooker loses very little, and you end up with a thin, watery stew. Cut the liquid in a stovetop or oven recipe by roughly half when you convert it. Going the other way, from slow cooker to oven, add liquid. And too little liquid in a slow cooker does not reduce, it burns: there is no stirring, and the base sits against the heating element.
Dried red kidney beans must never be cooked from raw in a slow cooker. Raw red kidney beans contain phytohaemagglutinin, a toxin that is destroyed by a hard boil of at least ten minutes. A slow cooker never reaches that temperature, even on HIGH, so the toxin survives the entire cooking time. This is a documented cause of serious food poisoning, with cases traced specifically to slow-cooked beans. Soak the beans, then boil them hard in a saucepan for at least ten minutes before they go anywhere near the slow cooker, or use canned beans, which are already cooked. This applies to red kidney beans above all, and the same caution is sensible for other dried beans.
Never start a slow cooker with a large frozen joint. The come-up time is slow by design, and a 2 kg frozen roast can sit between 4 °C and 60 °C for hours before its centre climbs out of that range. Food safety guidance calls that band the danger zone because it is where bacteria multiply fastest. Thaw the meat in the refrigerator first, always.
Do not lift the lid. Every time you take the lid off, the trapped heat escapes and the pot has to build it back up. Each look adds roughly 20–30 minutes to the total. If you want to check progress, lift the lid once near the end, not five times through the afternoon.
Milk, cream and most cheese go in at the end. Dairy proteins are sensitive to long, slow heat and will curdle or split over six hours. Stir cream, milk, crème fraîche or soft cheese through in the last 15–30 minutes, with the pot on LOW or off entirely. Hard, aged cheeses such as Parmesan are more tolerant and can go in earlier, but they will still turn stringy if cooked hard for hours.
Pressure cooker rules. Never fill the pot above two-thirds of its capacity, and never above one-half for anything that foams or expands, because foam can block the vent and the pressure has nowhere to go. Do not cook a dish thickened with flour or cornstarch straight in the pot without accounting for scorching: starch settles on the base and burns before the contents circulate. Thicken after cooking, or use a heat diffuser and stir carefully. Never pressure-cook applesauce, cranberries or pearl barley without real care, because all three foam heavily and are a known cause of blocked vents. Follow your manufacturer's manual over anything you read online, including this page.
Temperature minimums do not change with the appliance. Poultry must reach 74 °C in the thickest part of the meat, and ground or minced meat must reach 71 °C, whichever appliance cooked it. A slow cooker on LOW sits at around 93 °C, so it gets poultry there given time, but check with a probe rather than assume.
What Should Not Be Converted at All
A slow cooker is a braising tool, and it does its best work on tough, collagen-rich cuts that need a long, wet, gentle cook to turn tender: pork shoulder, lamb shank, beef chuck, chicken thigh. Push it outside that job and the results fall apart, often literally.
Crisp-skinned roast poultry cannot be converted, because the skin needs dry, hot air to crisp and a slow cooker provides the opposite. Anything relying on browning or evaporation fails for the same reason: the Maillard reaction needs surface temperatures well above 149 °C, and trapped steam keeps the surface wet. Cakes and quick breads need a dry oven. Seafood overcooks in minutes and turns to rubber over hours. Pasta cooked in the sauce turns to paste, so cook it separately.
Cuts That Convert Well, and Those That Do Not
| Ingredient | Converts? | Why |
|---|---|---|
| Pork shoulder, lamb shank, beef chuck | Yes, ideally | Collagen dissolves given long, wet, gentle heat |
| Chicken thighs, drumsticks | Yes | Dark meat tolerates long cooking; reaches 74 °C safely |
| Beef short rib, brisket, oxtail | Yes | Tough, fatty and collagen-rich; suited to braising |
| Root vegetables, onions, dried beans (pre-boiled) | Yes, with care | Cut evenly; put hard vegetables at the bottom |
| Chicken breast, lean steak, pork loin | No | Little connective tissue; dries out and turns stringy |
| Seafood, shellfish | No | Cooked in minutes; overcooks to rubber |
| Cakes, quick breads, pasta in sauce | No | Need dry heat or separate cooking; both turn to stodge |
| Raw dried kidney beans | Never | Toxin needs a 10-minute hard boil; slow cooker cannot do it |
Frequently Asked Questions
Roughly 8 to 10 hours. The rule of thumb is that one hour on HIGH is about two to two and a half hours on LOW, so multiply by two for the minimum and two and a half for the maximum. Use the lower end for dense cuts such as a whole shoulder, and the higher end for looser dishes such as soups and chillies. Both settings finish in a similar place, so the difference is mostly about timing convenience rather than the result.
No, not from raw. Dried red kidney beans contain phytohaemagglutinin, which is destroyed only by a hard boil of at least ten minutes. A slow cooker peaks around 149 °C on HIGH but the contents never boil hard, so the toxin survives. Soak and boil the beans in a saucepan for at least ten minutes first, or use canned beans, which are already fully cooked and safe to add straight to the pot.
Yes, cut it by roughly half if you are converting from an oven or stovetop recipe. A slow cooker traps steam, so almost nothing evaporates away, and a recipe that reduces by half over two hours in the oven will stay watery. Go the other way when converting a slow cooker recipe to the oven: add liquid, sometimes as much as double. Remember too that too little liquid does not reduce in a slow cooker; it burns on the base.
Not a large frozen joint. The slow come-up means a big frozen roast can sit between 4 °C and 60 °C for hours, which is the temperature band where bacteria multiply fastest. Thaw it in the refrigerator first. Small pieces such as frozen chicken thighs or stewing cubes are less risky because they thaw quickly, but thawing properly in the fridge costs you nothing and removes the doubt entirely.
Because almost no liquid evaporated. The lid trapped every drop of steam, so what went in is what is in the pot, minus a little absorbed by the meat and vegetables. Cut the liquid by around half next time, brown the meat first to add body, and finish with a slurry of cornstarch or a knob of butter if it needs thickening at the end rather than at the start.
In the last 15–30 minutes, with the setting on LOW or the pot switched off. Milk, cream and soft cheeses split under long, slow heat because their proteins are sensitive to sustained warmth. Stir them through at the end and let the residual heat bring them to serving temperature. Hard aged cheeses such as Parmesan are more tolerant and can go in a little earlier, though they turn stringy if cooked hard for hours.
If the slow cooker version is 6–8 hours on LOW or 3–4 hours on HIGH, the pressure cooker version is about 25–30 minutes at high pressure, around 15 psi. Add the time to come to pressure, which can be 10–15 minutes for a full pot, and the natural release, another 10–20 minutes. Do not fill above two-thirds, and never above one-half if the stew contains anything that foams.
Yes. Poultry must reach 74 °C in the thickest part of the meat whatever cooked it, and ground or minced meat must reach 71 °C. A slow cooker on LOW runs at roughly 93 °C, so it gets there given enough time, but the setting tells you nothing about the meat itself. Check with an instant-read probe before serving rather than trusting the timer.