Different safe manufacturers use different independent laboratories to test their products for fire protection. At the very least, a fireproof home safe should be able to protect the contents for a solid sixty minutes. You can always opt for a better fire rating, but this will naturally cost more.
Also, you may want to be very careful in the safe brands you purchase. Lesser-known companies have been known to just slap on these fire-rated labels without proper testing. This can also happen when you don't buy authentic safes. Chubbsafes, CMI Safe Co. safes, Diplomat safes, and Guardall safes are all trusted names you should look for.