Class K Fire: What It Is and How to Put It Out
Class K fires — burning cooking oil, grease, and fat — are the most dangerous fire most home cooks will ever face. Here is what they are, why they behave the way they do, and exactly how to stop one.
A Class K fire is a fire involving cooking oils, fats, and grease (called Class F outside the US). It burns hotter than ordinary fires and reignites easily, so it needs a Class K rated extinguisher — a wet chemical unit in commercial kitchens, or a compact multi-class extinguisher like the LifeSafe StaySafe All-in-1 (or a fire blanket for very small pans) at home. Never use water: it turns burning oil into a fireball.
Cooking is the leading cause of US home fires and home fire injuries, per NFPA cooking fire research.
What Is a Class K Fire?
A Class K fire is a fire that involves combustible cooking media — vegetable oils, animal fats, and grease. It is the classification defined by the US National Fire Protection Association (NFPA) specifically for kitchen appliance fires. Outside the United States the exact same fire is called Class F — so “Class K” and “Class F” describe identical fires with different regional labels.
Class K was added as its own category precisely because burning cooking oil does not behave like an ordinary Class B flammable liquid. Modern high-efficiency vegetable oils store an enormous amount of heat and burn at temperatures that ordinary extinguishing agents struggle to bring down. That combination — extreme heat plus a strong tendency to reignite — is what makes a grease fire so uniquely dangerous in a home or restaurant kitchen.
If you cook with a deep fryer, a wok, or a pan of oil, a Class K fire is the specific hazard you are protecting against. It is also the fire class that a standard ABC dry-powder home extinguisher is not designed to handle well.
For the full breakdown of every fire type, see our fire classes explained guide
Why Class K Fires Are So Dangerous
They Burn Hotter Than You Think
Cooking oil auto-ignites around 350–450°C and, once alight, burns far hotter than paper or wood. That heat is stored in the body of the oil, not just the flame — which is why simply blowing out or briefly covering the flame often is not enough.
They Reignite
A Class K fire can appear to be out and then flare back up seconds later because the oil is still above its ignition temperature. The correct extinguisher does two jobs at once: it smothers the flame and cools the oil below the point where it can reignite.
Water Turns Them Into Fireballs
The single most common and most dangerous mistake is throwing water on a grease fire. Water sinks, flashes to steam, and hurls burning oil into the air — a leading cause of kitchen burn injuries and rapid fire spread.
How to Put Out a Class K Fire (Step by Step)
Only ever fight a small, contained fire — and only if you have a clear exit behind you. When in doubt, get out.
Cut the Heat
Turn off the burner or appliance immediately. Removing the heat source stops adding energy to the oil and is the first step in any grease-fire response.
Smother It
If the fire is small and contained in a pan, slide a metal lid or a fire blanket over it to cut off oxygen. Leave it covered — lifting it too early lets air back in and can reignite the oil.
Use a Class K Agent
If flames are beyond the pan or you cannot safely cover it, use an extinguisher rated for Class K. Aim at the base of the fire from a safe distance and apply until the flame is out and the surface stops smoking.
Get Out If It Grows
If the fire spreads to cabinets or the range hood, do not keep fighting it. Evacuate everyone, close the door behind you if you can, and call the fire service from outside.
Which Extinguisher Works on a Class K Fire?
| Extinguisher / Agent | Class K? | Notes |
|---|---|---|
| Wet chemical (Class K rated) | ✅ Yes | The commercial standard. Cools the oil and forms a soapy foam (saponification) that seals the surface against reignition. |
| Multi-class aerosol (K rated) | ✅ Yes | Compact home option. The StaySafe All-in-1 is rated for Class K plus A, B, C and lithium-ion in one 9-oz can. |
| Fire blanket | ✅ Small pans | Excellent for a single burning pan — smothers the flame with no mess. Not suited to a spreading fire. |
| ABC dry powder | ❌ Not rated | Can blast burning oil out of the pan and does little to prevent reignition. |
| CO₂ | ❌ Poor | The high-pressure jet can splash oil, and it does not cool the oil enough to stop reignition. |
| Water / water mist | ❌ Dangerous | Creates a fireball. Never use water on burning cooking oil. |
Wet chemical (Class K rated)
Multi-class aerosol (K rated)
Fire blanket
ABC dry powder
CO₂
Water / water mist
Agent suitability based on fire class ratings and NFPA guidance for cooking-oil fires.
Home Kitchen vs Commercial Kitchen
Commercial kitchens are required to protect deep fryers and cooking ranges with dedicated Class K wet chemical systems, typically alongside a fixed hood-suppression system installed to the NFPA standard for commercial cooking equipment. Those systems are designed for high-volume fryers and continuous cooking.
In a home kitchen you do not need an industrial wet chemical canister. What you need is something you can grab in seconds and use with one hand: a compact multi-class extinguisher that explicitly lists Class K on the label, or a fire blanket kept within reach of the stove for small pan fires. The mistake most households make is relying on a generic ABC dry-powder unit that was never rated for grease fires in the first place.
Our top compact pick, the LifeSafe StaySafe All-in-1, covers Class K along with A, B, C, electrical, and lithium-ion in a single can — which is why it is the unit we recommend keeping within six feet of the stove.
The Compact Class K Pick
The LifeSafe StaySafe All-in-1 is rated for Class K grease fires plus four more fire types in a 9-oz format that fits in a kitchen drawer.
Frequently Asked Questions
Protect Your Kitchen From Class K Fires
A grease fire needs a Class K rated response — not water, and not a generic dry-powder unit. The StaySafe All-in-1 covers Class K plus A, B, C, and lithium-ion in a single compact can.