Installation

Safe sizes: what size do I really need?

From 3 to 84 folders: how to realistically estimate the space required, why internal and external dimensions differ so much, and why almost everyone buys them too small.

Last reviewed on 12. August 2026 1 min read by Tim Herberger, Fachredaktion bei Bremer Tresor

Size is the decision that is regretted most often. The most common phrase heard after a purchase is: I should have gone bigger. This is because almost everyone only accounts for today's contents and not what will be added over the coming years.

Size in 2 questions

Which size is right for you?

Do not calculate in liters, but in folders. This is the unit that is easiest to visualize, and our models are specified exactly accordingly.

Scale

How much fits in which safe?

Our range extends from 3 to 84 folders in capacity, which corresponds to approximately 4 to 866 liters of volume. This range covers everything from a furniture safe for jewelry and IDs to a double-door safe for law firm archives.

Size category Approximate height Typical contents
small 35 to 60 cm jewelry, cash, IDs, up to approx. 6 folders
medium 60 to 105 cm 8 to 12 folders plus laptop and valuables
large 110 to 185 cm up to 30 folders
extra large from 150 cm 30 to 50 folders, files and collections
huge double-door up to 84 folders, archive format for law firms and practices
Note

Inner and outer dimensions vary significantly

A safe's wall thickness is not just sheet metal, but a multi-layer composite of steel and special concrete. The higher the resistance grade, the thicker the wall. For fireproof safes, an insulating layer is added.

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Always calculate with the inner dimensions. Two safes with identical outer dimensions can differ significantly in usable interior space if their resistance grade or fire protection level is different. The outer dimensions matter for the placement location; for your contents, only the inner dimensions count.

Also, keep the shelves in mind. They are generally height-adjustable but take up some vertical space themselves. Anyone wanting to stand folders upright needs about 32 centimeters of clear height per level.

Recommendation

Better one size too big

A safe is purchased for decades, and the contents almost always grow. Documents are added, jewelry is inherited, contracts accumulate. The price difference for the next size up is usually significantly lower than the cost of a second purchase, including re-delivery and anchoring.

Two things that increase with the larger version and should be planned for: the weight, which determines the transport route (see installation site), and the footprint. We will clarify both with you before delivery.

Related to this guide

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Tim Herberger
Tim Herberger
Fachredaktion bei Bremer Tresor

Tim Herberger schreibt die Ratgeber von Bremer Tresor. Er bereitet Normen, Vorschriften und Praxiswissen so auf, dass daraus eine klare Kaufentscheidung wird, und gleicht jeden Text mit unseren Fachleuten aus Beratung und Service ab.

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Frequently asked questions

How do I correctly estimate the space required?
Do not calculate in liters, but in binders. This is easiest to visualize, and our models are specified exactly accordingly. The range extends from 3 to 84 binders, which corresponds to approximately 4 to 866 liters.
Why is the interior smaller than expected?
The wall is a multi-layered composite of steel and special concrete
How much height do I need for binders?
Around 32 centimeters of clear height per level if the binders are to stand upright. The shelves are generally height-adjustable, but take up some height themselves.
Is it worth going one size bigger?
As a rule, yes. Contents almost always grow over the years, and the surcharge for the next size up is significantly smaller than a second purchase including delivery and anchoring. You should plan for the higher weight and larger footprint.