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What's the Difference Between Combustible and Flammable Materials?
We break down the differences between combustible and flammable materials, plus safety measures to implement to minimize the risk of fire and explosion.Byline: BTB Author
October 24, 2025 / Time to read: 5 minMany everyday materials — from aerosol deodorants, batteries, nail polish remover and paint thinner are more dangerous than they may appear. In fact, when you look at their labels, you'll find warning signs that the contents can be either combustible or flammable. While these terms often get mixed up, there is a difference. Understanding that difference is a matter of safety, control and disaster prevention.
Keep reading to learn about the key differences between combustible vs. flammable materials, hidden risks they present and how to handle them safely.
What Do Combustible and Flammable Mean?
Combustible and flammable refer to
Combustible materials can catch fire, but they require a higher temperature to ignite. Generally, these materials have a flashpoint (the lowest temperature at which they can catch fire) above 100°F. They won’t ignite as easily as flammable substances, but given enough heat or an open flame, they'll burn.
Flammable materials ignite at lower temperatures, with a flashpoint below 100°F. This lower threshold means they can catch fire more readily at room temperature, making them more dangerous in environments where sparks or static electricity may be present.
While the flashpoint thresholds are used to classify liquids as flammable and combustible, the same principles generally apply to solid materials that can burn when exposed to heat or flame.
Examples of Combustible Materials
These materials are typically safe in cool or controlled environments but pose a fire risk if exposed to open flames or high temperatures.
- Wood: Wood requires relatively long, direct exposure to flames or high temperatures to ignite.
- Paper and cardboard: These cellulose-based products ignite more readily than some other combustibles, but they still require higher temperatures than flammable liquids.
- Diesel fuel: Diesel has a higher flashpoint than gasoline and doesn’t ignite easily at room temperature. It requires a direct flame or high-pressure environment.
- Certain oils: Many oils, including cooking oils, motor oils and lubricants, are combustible.
- Coal and charcoal: These carbon-based materials are often used as fuel but need sustained heat to reach ignition.
- Furniture and fabrics: Many household items made from natural fibers — like cotton and wool — are combustible. While these items don’t easily catch fire at room temperature, they can burn intensely if exposed to an open flame.
- Rubber: Although it doesn’t ignite easily, rubber is combustible. Once ignited, it can sustain a hot, smoky fire.
- Certain types of plastic: Some plastics, like polyethylene and polypropylene, are combustible and will burn under sustained heat.
Examples of Flammable Materials
Flammable materials can ignite easily at low temperatures. Most are liquids or gases.
- Gasoline: The flashpoint of gasoline is around -45°F, making it extremely easy to ignite. It is one of the most hazardous and commonly used fuels due to its low ignition threshold and high volatility.
- Ethanol and other alcohols: Ethanol, isopropanol and methanol are commonly used alcohols with flashpoints below 100°F. You can find them in cleaning solutions, hand sanitizers and certain laboratory chemicals.
- Acetone: This flammable chemical, often used in nail polish removers and as an industrial solvent, has a flashpoint of around -4°F. Its vapors can be reactive with air, making it a serious fire hazard.
- Propane: Propane, used as a fuel for heating, cooking and vehicles, is highly flammable. Stored as a compressed gas, it can easily ignite with a spark.
- Butane: Commonly used in lighters and as a fuel for small stoves, butane is a flammable gas with a low ignition point.
- Paint thinner: Paint thinners and similar solvents often contain flammable chemicals, such as toluene and xylene, which can easily ignite in poorly ventilated areas. Some paint thinners have higher flashpoints, making them combustible rather than flammable.
- Hydrogen: Hydrogen is one of the most flammable substances in the world. When mixed with air, it forms a highly explosive mixture, which is why it requires strict handling and storage protocols.
- Aerosol sprays: Many aerosol products, such as deodorants, hairsprays and cleaning agents, contain flammable propellants, including propane, butane and ethanol. These can ignite if exposed to heat or sparks.
- Lighter fluid: Made from naphtha or similar hydrocarbons, lighter fluid is highly flammable. Because it ignites easily, it is convenient for lighting grills or campfires.
- Solvents: Many industrial solvents are flammable and have low flashpoints, making them hazardous in manufacturing and laboratory environments.
Hazards Associated with Combustible and Flammable Materials
- Fire risk
Combustible materials may not ignite as easily as flammable materials. Once they do, however, they can produce intense flames and burn for a long time, which may lead to the rapid spread of fire in a building or outdoor environment. - Smoke and toxic fume production
When combustible and flammable items burn, they often release large amounts of smoke and potentially toxic fumes. Materials like rubber, certain plastics and treated wood, for instance, can emit hazardous gases, such as carbon monoxide, cyanide and dioxins. - Explosion risk
In enclosed or poorly ventilated areas, combustible and flammable gases can reach explosive levels if exposed to heat or an ignition source. - Difficulty extinguishing
Some materials, such as oils, rubber and certain plastics, are challenging to extinguish once they catch fire. Water may be ineffective or even dangerous, as in the case of fires involving grease or oil. Putting these kinds of fires out requires specialized firefighting agents, such as foam or dry chemicals. - Environmental impact
Flammable and combustible materials, when spilled or burned, can contaminate soil, water and air.
Safety Measures to Mitigate the Dangers of Combustible and Flammable Materials
While many of these guidelines apply more to certain work settings, implementing these safety measures at home can help minimize the risk of fires, explosions and other hazards associated with storing and handling combustible and flammable materials.
- Store properly
Store flammable and combustible materials in designated, well-ventilated areas away from ignition sources. - Maintain cool storage conditions
Keep flammable and combustible items away from heat sources, direct sunlight or equipment that generates heat. - Ensure proper ventilation
Proper ventilation helps disperse vapors that could build up and create flammable mixtures. - Use proper containers
Keep flammable and combustible materials in their original containers. - Have the right equipment on hand
Keep fire extinguishers or foam extinguishers near storage and handling areas. - Conduct routine inspections
Conduct regular inspections of storage areas, containers and fire-safety equipment to identify and address potential hazards, leaks or outdated equipment. - Avoid open flames and sparks
Be aware of equipment that may produce sparks and do not smoke near combustible or flammable materials.
Handle with Care: Protect Yourself and Others
Many of the materials we use at work and at home have the potential to cause fire if not handled properly. By recognizing which items are flammable or combustible — and what precautions to take to reduce the chances of an accident — you can help protect lives, property and the environment.
At Republic Services, we know emergencies like spills and fires can happen anytime. To learn more about our 24/7 emergency services for businesses, visit our
