Fireproof safe ratings tell you two things: how hot the inside of the safe is allowed to get, and for how long. The trouble is that two very different kinds of rating get described with the same word. A UL 72 classification such as “Class 350, 1 hour” comes from a standardized test run by an independent lab. A line like “1,400 degrees for 30 minutes” on a product page is a manufacturer’s claim about the fire the safe was exposed to. This guide explains both, so you can compare safes honestly and pick the right protection for documents, media and firearms.
How fireproof safe ratings work
The main North American standard is UL 72, “Tests for Fire Resistance of Record Protection Equipment.” UL’s own standards store describes it as covering “the test procedures applicable to the fire-resistance classification of record protection equipment” (UL Standards, UL 72). The current edition was published in January 2026.
A UL 72 label has two parts:
- The class (350, 150 or 125) is the maximum interior temperature in degrees Fahrenheit the contents may reach during the test.
- The duration (for example 1/2 hour, 1 hour or 2 hours) is how long the safe sat in the furnace while holding that limit.
Besides the fire endurance test, rated safes can go through an explosion test and an impact test. FireKing describes its UL impact rating as a 30 foot drop onto bricks and concrete, after which the unit is inverted and reheated (FireKing). A UL fire rating is about heat, not burglary; burglary resistance is rated separately.
UL Class 350, 150 and 125: fire rated safe for documents vs media
The class you need depends on what you are storing. Paper chars at a much higher temperature than film, tape or older magnetic disks can tolerate.
| UL 72 class | Interior limit | Intended contents |
|---|---|---|
| Class 350 | Below 350°F | Paper records: deeds, passports, certificates, cash |
| Class 150 | Below 150°F and below 85% humidity | Paper plus nonpaper records such as magnetic tape and photographic film |
| Class 125 | Below 125°F and below 80% humidity | Also flexible computer disks; often marketed for digital media |
Limits and humidity figures are from Liberty Safe’s fire rating guide. One caution: Class 125 was written around flexible disks, and newer devices have their own heat limits. If you store hard drives, USB sticks or optical discs, check the device maker’s storage temperature and keep a second copy offsite or in the cloud.
UL Class 350 1 hour: what the test looks like
FireKing, which sells UL labeled files and safes, lists the furnace conditions for its Class 350 ratings: up to 1,550°F for 1/2 hour, up to 1,700°F for 1 hour and up to 1,850°F for 2 hours, with the interior kept below 350°F (FireKing ratings and certifications). A dealer explainer adds that the safe also cools down inside the furnace, and that temperature and humidity can keep climbing during that cooling period, which is where many units fail (Safe and Vault Store).
Liberty Safe describes 30 minutes as basic protection, 1 hour as the recommended home standard, and 2 hours or more for rural homes, commercial buildings or highly valuable items (Liberty Safe).
Fireproof vs fire resistant safe
No safe is truly fireproof. Liberty Safe says it plainly: safes are fire resistant for a specified duration. “Fireproof” is a marketing word; “fire resistant for X minutes at class Y” is the useful part.
You will see three kinds of fire claims:
- UL 72 classified. Tested by UL to a published method, with a class and duration on the label.
- Other third party ratings. FireKing, for example, lists some products with Intertek ETL fire ratings, which are independent tests but not UL 72 labels.
- Manufacturer ratings. Tested in house or by an unnamed lab and stated as an outside temperature and time, such as “1,200°F for 30 minutes.” FireKing itself lists in house ratings alongside its UL ones and labels them as manufacturer ratings.
A manufacturer rating is not automatically weak, but it answers a different question. “1,400°F for 30 minutes” describes the heat outside the box. It does not tell you the interior limit, the cool down conditions, or whether an explosion or drop test was run, so it is not a like for like comparison with a UL class.
Gun safe fire rating: reading the listing
Most residential gun safes carry a manufacturer fire rating rather than a UL 72 class. Here is what our own safe listings state:
- The 8.47 cu ft Tall Fireproof Safe Vault, 11.87 cu ft Tall Fireproof Safe Vault and 19.97 cu ft Tall Fireproof Safe Vault listings state fire resistance under 1,400°F for 30 minutes, with an electronic keypad and backup key.
- The 36 Gun Safe and 40 Gun Safe listings state a 1,400 degree fire rating for 30 minutes. The 36 Gun Safe listing also mentions an intumescent door gasket that expands during a fire to seal the door.
- Smaller units such as the 1.91 cu ft Keypad Fireproof Jewelry Safe and 2.75 cu ft Keypad Fireproof Jewelry Safe state up to 1,200°F for 30 minutes.
These are manufacturer ratings. The listings do not name a UL 72 class, an interior temperature limit or a test lab, so do not treat them as UL Class 350 equivalents. If you need a specific certification for insurance or business records, call us before ordering and we will check with the supplier.
Fire seals keep heat out, but they also keep moisture in. Our gun safe dehumidifier guide covers humidity control, and options like the Mesa Safe Dehumidifier MD24 are listed under Mesa Safe.
Where to put a fireproof safe
Placement affects how a rating plays out in a real fire.
- Lower floors. Liberty Safe notes that a safe on an upper floor may fall through a collapsing floor, which is why the UL impact test exists. A ground floor or slab location avoids that risk.
- Think twice about the garage. Liberty Safe also points out that garages and workshops can see hotter, faster fires because of the fuels stored there. If the garage is the only option, keep the safe away from fuel cans and solvents. Our NewAge garage cabinets review covers organized storage if you are planning the space.
- Anchor it. Several of our safe listings mention included mounting hardware. Follow the manual for bolt type, floor type and hole locations, and hire a pro for concrete or upper floor installs.
How to choose
- List what goes inside: paper only, or film, tape and drives too.
- Pick the class that matches the most heat sensitive item.
- Pick a duration based on how fast fire crews can reach you; rural homes often justify longer.
- Check who did the test: UL 72, another independent lab, or the manufacturer.
No rating is a guarantee that contents will survive a specific fire. Ratings describe test conditions, and real fires vary. For more category guides, see our buying guides.
Frequently asked questions
Is UL Class 350 good enough for documents?
For paper, yes. Class 350 is intended for paper records and keeps the interior below 350°F for the rated time. Choose the duration based on your risk; Liberty Safe calls 1 hour the recommended home standard.
Can I store hard drives in a Class 350 safe?
Not with confidence. Media needs a much cooler interior. Use a Class 125 rated container or one the manufacturer rates for digital media, and keep a backup copy offsite.
Is a 1,400°F, 30 minute gun safe the same as UL Class 350, 1/2 hour?
No. The first is a manufacturer statement about outside heat. The second is a UL test with a defined interior limit and cool down. They may perform differently, and the listing alone cannot tell you which is better.
What is the difference between a fireproof and a fire resistant safe?
Every safe is only fire resistant for a limited time. Read the class, duration and test source instead.
How do I get help choosing a safe?
Call 866-777-2590, Monday to Friday, 9AM to 6PM PST. Orders of $999 or more ship free by freight; smaller orders ship for a flat $200. See our return and refund policy before you buy.
