How to Tell If Cooking Oil Is Hot Enough for Frying

You can tell if it's boiling hot without a thermometer

Deep frying of elder blossoms
Silvia Jansen/Photodisc/Getty Images

No matter the type of cuisine, they all include some dishes that require frying. Whether it's meat, seafood, or vegetables, it all starts out the same way: with a pan of hot oil. It's easy enough to just pour oil into a pan, but how do you know when the oil is the right temperature for frying? It's obviously easier if you have a kitchen thermometer, but it's possible to get it right without one as well.

If you have a thermometer, just check the oil to find out the temperature. The ideal oil temperature for most frying is between 350 and 365 F. If your thermometer says that, you're good to go.

Finding the Oil Temperature 

But without a thermometer, how do you know when your oil is ready to go? One way is to drop a kernel of popcorn into the oil. If the popcorn pops, it tells you the oil is between 325 and 350 F, in the right temperature range for frying. The easiest and safest method is to stick the end of a wooden spoon into the oil. If you see many bubbles form around the wood and they start to float up, your oil is ready for frying. If it is bubbling hard, the oil is too hot; let it cool a bit and check the temperature again. Another method that's often suggested is to add a drop or two of water to the oil. But oil and water do not mix, and you can get a nasty burn if it splashes up at you, and it's advised that you avoid this method.

Why Oil Temperature Matters

If the oil is too hot, the food will burn on the outside before cooking on the inside. But the more common problem with oil temperature is that it's too low, and that causes the food to start absorbing the oil. So, if you've eaten fried food that tasted overly greasy, chances are it was fried at too low a temperature.

Choosing the Right Oil

There are plenty of choices of cooking oil, and it can be confusing when you're standing in the grocery aisle trying to decide which one to buy.

Vegetable oil is one of the most commonly used because it has a relatively high smoke point. Also common is canola oil, which is healthier than vegetable oil because of its lower saturated fat and higher monounsaturated fat content. It's best for medium frying temperatures, up to about 450 F, but that works for most household frying needs.

Likewise, corn and sunflower oils are reasonably healthy and appropriate for medium frying temperatures.

For truly high-temperature frying, choose peanut oil for its high smoke point.

Olive oil is the healthiest of all the oils and is great for salad dressings and low-temperature frying needs. But it has a low smoke point, so it's generally not the ideal choice for deep frying.

Whatever oil you use, store it at room temperature in a dry, dark place, and it will keep for about a year. After frying, discard the oil by pouring it into a leak-proof container and putting it in the trash, not down your kitchen sink drain or disposal.