This is a difficult question to answer. Many variables would determine the range of a 5 watt HT. All of the following factors would affect range:
-Efficiecy of antenna. Most use "rubber duck" types which are VERY inefficient. There are some "after market" (and longer) antennas available for most radios which ARE more efficient giving your radio more gain for transmitting and receiving.
-Terrain. Range is much better over flat, unobstructed ground. Trees, hills, buildings, powerlines, etc., all have a negative impact on range.
-When talking through a repeater with a HIGH antenna, range can be greatly improved. When working with other ground level HTs directly (SIMPLEX), range is limited by terrain, obstructions, etc.
IN GENERAL....I have found that a typical 5 watt HT in an crowded urban area has a SIMPLEX range of abount 1 or 2 miles, or less. That's talking directly with another HT. Yes, you might be able to talk farther, but not reliably. That same HT communicating through a repeater with a HIGH antenna can reliably reach that repeater 5-10 miles out in the same urban environment. Distances would be much greater over flat, open country, like along the beach, etc.
I have easily talked simplex distances of 40-50 miles (and even more) when located on a high mountaintop, like Pikes Peak.
So, there is no simple answer to your question without knowing all the parameters involved in your situation.