A recipe that says one hour in the oven is no help when you want to use the slow cooker instead. The two methods cook in completely different ways: an oven uses dry, direct heat, while a slow cooker uses gentle, moist heat over many hours. This converter bridges that gap. Enter the oven time from your recipe, and it gives you the matching slow cooker times on both the low and high settings, so you can start dinner in the morning and come home to a finished meal.
The conversion follows a standard table that home cooks have used for years. Up to 30 minutes in the oven becomes about 4 hours on low or 2 hours on high. An oven time of up to 1 hour becomes about 6 hours on low or 3 hours on high. Up to 2 hours in the oven becomes about 8 hours on low or 4 hours on high. Anything longer than 2 hours in the oven is roughly 10 hours on low or 5 hours on high. Notice that the high setting is always about half the low time, which is a useful rule when a recipe only gives one setting.
Here is a worked example. Your casserole recipe says 45 minutes in the oven. That falls in the up-to-1-hour band, so the converter gives 6 hours on low or 3 hours on high. If you leave home at eight in the morning and return at six in the evening, the low setting fits your day, with the dish finishing around two in the afternoon and staying warm until you eat. If you start at two in the afternoon instead, the high setting finishes the same dish by five, just in time for dinner.
The type of food matters as much as the time. Tough cuts of meat, dried beans, and root vegetables love long, slow cooking, because the gentle heat breaks down tough fibres and turns them tender. Delicate foods do not: fish, dairy, and fresh herbs can break down or turn grainy if they cook for eight hours, so add those near the end instead. Pasta and rice also absorb liquid over time, so add them in the last hour or cook them separately if your recipe depends on their texture.
How full the pot is changes the cooking time too. A slow cooker works best when it is between half and three-quarters full. A pot that is too empty overheats the food and dries it out, while a pot filled to the brim heats slowly and may leave the centre undercooked. If your pot is very full, add an extra hour on low. If you are cooking from frozen, add even more time, and never cook large frozen joints in a slow cooker, because the centre stays too cool for too long.
Liquid is the other big difference between oven and slow cooker recipes. An oven loses moisture to evaporation, but a slow cooker traps almost all of it under the lid, so a recipe converted from the oven usually needs less liquid. As a starting point, use about a third less liquid than the oven version calls for, and resist lifting the lid to check: every lift drops the temperature and can add twenty to thirty minutes to the cooking time. Trust the timer instead.
Use this converter as a planning tool, not a guarantee. Check meat with a thermometer, taste sauces before serving, and adjust for your own cooker, because brands run hotter or cooler than each other. Write down what worked for your favourite dishes, so next time you already know your own conversion. With a reliable table and a little practice, any oven recipe can become a slow cooker recipe, and dinner can cook itself while you get on with your day.