The pilot of a small single engine airplane visually checked the aircraft's fuel tank quantity during preflight; but ran out of fuel before his destination because the quantity gauges and his visually estimated fuel were both inaccurate.

Narrative

When I did my preflight I checked my fuel prior to takeoff and estimated that I had 22 to 25 gallons. Upon engaging the master switch; the fuel gauges agreed with my fuel check. I was flying a cross country flight and calculated that I had enough fuel to make it to an intermediate airport for fuel. As I was getting closer to the fuel stop airport I thought that the fuel gauge was dropping quicker than normal. When I got to within seven miles of the airport I canceled my Flight Following with Approach. Next; I contacted the airport on their common radio frequency stating my callsign; position; and my intentions of landing. Another pilot waiting to takeoff asked what my location was and I stated about five miles south inbound for a landing. He said he was about 45 seconds from taking off and could wait. I responded and said that I needed to land because I was getting short on fuel. At this point the right tank gauge showed to have about 6 to 7 gallons left; which should have given me about 40 more minutes of flying time. At this time I had descended to about 3;500 FT from 4;500 FT to start preparing for my landing. At this time the engine quit and I immediately set my glide speed to 90 MPH and picked a spot out to land if I could not make the runway. I got about 300 yards from the runway and determined that my glide slope was not going to make it to the runway so I made a left bank and landed in an open field heading southwest. To prevent recurrence I will fill my tanks up on the return trip.