Smoke Points Explained: Which Oils for Which Heat
BeginnerQuick Answer
Smoke point is the temperature at which an oil visibly smokes and starts to chemically degrade. When oil smokes, it's producing free radicals and acrolein, a compound that tastes acrid and may irritate your airways. Different oils smoke at different temperatures depending on how much they've been refined and how many free fatty acids they contain.
The Science
The smoke rising from a hot pan of oil is a warning. But what exactly is it warning you about? And is it as serious as many food writers suggest?
The answer is more complicated than most oil guides let on. Let’s look at what’s actually happening chemically when oil hits its smoke point, and then separate the real concerns from the myths.
What Smoke Point Means
Smoke point is the temperature at which an oil begins to produce a continuous, visible stream of smoke. Below that temperature, you might see wisps. At the smoke point, the oil is actively degrading.
The degradation that produces smoke is a combination of processes. Free fatty acids (FFAs), fat molecules that have broken away from their glycerol backbone, are volatile enough to vaporize. Trace compounds in unrefined oils (chlorophylls, proteins, carbohydrates) also burn off. The smoke you see is these compounds turning to vapor and then breaking down further in air.
The most concerning compound that forms is acrolein (2-propenal). It’s a byproduct of glycerol degradation. Glycerol is the backbone molecule in all triglyceride fats, and when it overheats, it loses water molecules and forms acrolein. Acrolein is what makes overheated oil smell sharp and eye-watering. It’s classified as a potential respiratory irritant at high concentrations. In a well-ventilated kitchen, the risk is low. In a poorly ventilated space, repeatedly cooking with overheated oil is worth avoiding.
Beyond acrolein, overheated oils also generate free radicals, highly reactive molecules with unpaired electrons. Free radical production increases as oil degrades, and the degraded oil loses its nutritional value. Polyunsaturated fats are especially susceptible to this kind of oxidative breakdown.
Why Smoke Points Vary So Much
Two main factors determine where an oil’s smoke point falls.
Free fatty acid (FFA) content: All oils contain some FFAs, individual fatty acid molecules not attached to a glycerol backbone. FFAs are more volatile and more prone to oxidation than intact triglycerides. Oils with higher FFA content have lower smoke points. Fresh, high-quality oils have lower FFA content. Oils that have been exposed to heat, light, or air develop more FFAs over time.
Refinement level: Unrefined or cold-pressed oils retain more of the natural compounds from the source: chlorophylls, waxes, proteins, phospholipids. These compounds are relatively unstable under heat and begin to smoke and burn at lower temperatures than pure triglycerides would. Refined oils have had most of these compounds removed through filtering, bleaching, and deodorizing. The result is a cleaner oil with a higher smoke point but less flavor and fewer trace nutrients.
This relationship also explains why the same oil can have a smoke point range rather than a single number. Extra virgin olive oil is often cited at 375-405°F. The variation comes from differences in FFA content and olive variety. A fresh, high-quality EVOO with very low acidity (less than 0.3% FFA) can hit 410°F. An older, lower-quality EVOO might smoke below 375°F.
Smoke Point Chart
Here are approximate smoke points for common cooking fats. Treat these as useful guides, not exact numbers. Batch variation is real.
| Oil / Fat | Smoke Point (°F) | Smoke Point (°C) | Notes |
|---|---|---|---|
| Avocado oil (refined) | 520°F | 270°C | Highest smoke point of common cooking oils |
| Ghee | 485°F | 252°C | Milk solids removed, very stable for high heat |
| Vegetable/soybean oil | 450°F | 232°C | Refined, neutral flavor |
| Canola oil (refined) | 400°F | 204°C | Widely available, neutral |
| Coconut oil (refined) | 400°F | 204°C | Higher than unrefined. Little coconut flavor |
| Extra virgin olive oil | 375–405°F | 190–207°C | See myth section below |
| Avocado oil (unrefined) | 375°F | 190°C | More flavor, lower smoke point |
| Butter | 300–350°F | 148–177°C | Milk solids burn. Use clarified butter for high heat |
| Unrefined coconut oil | 350°F | 177°C | Strong coconut flavor. Not ideal for high heat |
| Unrefined walnut oil | 320°F | 160°C | Best used cold or as a finishing oil |
For reference: a typical sauté runs around 250-350°F. Deep frying is usually 350-375°F. A ripping-hot cast iron for searing can reach 500°F+.
The Olive Oil Myth
“You can’t cook with extra virgin olive oil” is one of the most persistent myths in food media. It’s wrong, or at least much more conditional than it sounds.
Here’s what the evidence actually shows. A 2018 study published in the journal ACTA Scientific Nutritional Health tested multiple cooking oils under realistic frying conditions and found that extra virgin olive oil was the most stable, producing the fewest harmful polar compounds, even at high temperatures. The high polyphenol content of EVOO appears to act as an antioxidant, protecting the oil from oxidative degradation.
At the temperatures used in typical home cooking (sautéing at 300-350°F, roasting at 375-400°F) EVOO performs well. Its smoke point sits within or above that range. For the vast majority of home cooking applications, EVOO is fine.
Where the caution has some merit: for very high-heat applications like searing on a cast iron (where the pan can hit 450-500°F), a refined high-smoke-point oil is a better choice. Not because of safety concerns, but because EVOO will start smoking before you want it to, and the delicate flavor compounds in EVOO (the thing you’re paying for) get destroyed by that level of heat anyway. Use refined avocado oil or ghee for extreme heat, and save your good olive oil for where you can taste it.
Matching Oils to Heat Applications
Instead of memorizing smoke point numbers, think in terms of temperature zones.
Very high heat (450°F+): Searing, wok cooking, deep frying
- Best choices: refined avocado oil, ghee, refined coconut oil, refined vegetable or peanut oil
- These oils are stable enough to handle extreme heat without smoking and breaking down
Medium-high heat (350-450°F): Most sautéing, roasting, stir-frying
- Best choices: extra virgin olive oil, canola oil, coconut oil (refined)
- EVOO is genuinely fine here, and its flavor often improves roasted vegetables
Low to medium heat (under 350°F): Eggs, gentle sautéing
- Butter works well here. Its milk solids contribute flavor and it doesn’t get hot enough to burn in this range
- EVOO, light olive oil, most oils work fine
No heat: Dressings, finishing, dipping
- This is where unrefined, flavorful oils shine: unrefined walnut, hazelnut, toasted sesame, finishing-quality olive oil
- Never waste these on high-heat cooking. Their delicate flavors are destroyed at temperature
How Repeated Use Affects Smoke Point
Every time you use oil, its smoke point drops. Heat breaks down triglycerides into FFAs. Each fry session adds more FFAs to the oil. This is why commercial fryer oil needs to be changed regularly, and why the oil in a home fryer shouldn’t be reused indefinitely.
Visual cues that oil is degrading: it darkens, becomes more viscous, foams excessively around food, and smells stale or acrid. When your frying oil shows these signs, it’s time to replace it.
If you do reuse frying oil, strain it through a fine mesh strainer to remove food particles (which accelerate degradation), store it in a cool, dark place, and track how many uses it’s had.
Deep dive: The chemistry of oil oxidation and what "free radicals" actually means
When food writers say overheated oil “produces free radicals,” they’re describing a specific chain reaction called lipid oxidation (or lipid peroxidation for polyunsaturated fats).
A free radical is a molecule or atom with an unpaired electron. Unpaired electrons are highly reactive. They’ll grab an electron from a neighboring molecule to achieve stability. When they do, that neighboring molecule becomes a radical itself. This is the “chain reaction” part: one radical generates another, which generates another, in a cascade that can continue until the system runs out of susceptible molecules or encounters a molecule that terminates the chain.
In oils, the most susceptible molecules are polyunsaturated fatty acids (PUFAs). Double bonds in PUFAs are vulnerable to attack by reactive oxygen species and other radicals. When a PUFA is oxidized, it forms a lipid peroxide, an unstable compound that breaks down into secondary products including aldehydes (like hexanal and malondialdehyde) and acrolein.
Saturated fats have no double bonds, making them much more resistant to this kind of oxidation. Monounsaturated fats (like the oleic acid in olive oil) have one double bond and are moderately resistant. PUFAs like linoleic acid (two double bonds) and especially alpha-linolenic acid (three double bonds) are highly susceptible.
This is why oils high in PUFAs (flaxseed oil, walnut oil, hemp oil) degrade very quickly under heat and should never be used for cooking. It’s also why oxidative stability, not just smoke point, matters when choosing a cooking oil. An oil can have a high smoke point but still degrade rapidly through oxidation below that temperature.
Antioxidants like vitamin E (tocopherols) and polyphenols interrupt the radical chain reaction. Oils naturally high in these compounds (including extra virgin olive oil) have better oxidative stability than their smoke points alone would suggest.
What This Means for You
Match your oil to your task. Use refined avocado oil or ghee for high-heat searing. Use extra virgin olive oil for sautéing and roasting at normal temperatures (up to about 400°F). The smoke point concern is overblown for typical home cooking. Save unrefined, flavorful oils like toasted sesame or unrefined walnut oil for finishing and dressings, never for cooking.
References
- Ewert A, Granvogl M, Schieberle P. (2014). Isotope-labeling studies on the formation pathway of acrolein during heat processing of oils. J Agric Food Chem. 62(33):8524-9.
- Casal S, Malheiro R, Sendas A, Oliveira BPP, Pereira JA. (2010). Olive oil stability under deep-frying conditions. Food Chem Toxicol. 48(10):2972-9.
- Pellegrini N, Visioli F, Buratti S, Brighenti F. (2001). Direct analysis of total antioxidant activity of olive oil and studies on the influence of heating. J Agric Food Chem. 49(5):2532-8.
- McGee H. On Food and Cooking: The Science and Lore of the Kitchen. Scribner, 2004.
- Belitz H-D, Grosch W, Schieberle P. Food Chemistry. 4th ed. Springer, 2009.
- USDA Agricultural Research Service. USDA National Nutrient Database — Fats and Oils.