This is a harder question to answer than may readily be apparent.
Many factors come into play in determining the chances for success in a given dungeon.
Without full knowledge of your character's abilites, weaknesses, and resources it is impossible for anyone else to answer the dungeon level question reliably. What you can get from others is a sense of what it takes to conquer a dungeon. Knowing that someone else was able to survive, and perhaps even flourish, in a dungeon at a given level is useful in gauging your own potential for success. The information becomes more reliable with the more people from whom you hear. If twenty people were able to make it through a dungeon when they were level 10, chances are you can too.