How to buy a safe. If your goal is to protect irreplaceable items such as jewelry, guns, documents, family photos, birth certificates, passports, and tax records while keeping them in your house, a home safe could be a relatively inexpensive, convenient and trusted solution. An easy way to figure out how big of a safe you will need is to collect everything you plan to store in it and take measurements. Regular home safe capacity is 1.2 to 1.3 cubic feet, which should accommodate a foot-high stack of 8 by 11-inch documents. Our home safes are designed to protect your valuables from fire, theft, or both. Some of our safes are also water resistant. We test safes here at BUY a SAFE and many are tested by independent organizations such as Underwriters Laboratories (UL) and Intertek (which uses the ETL mark).