Wish to point out that for some cars, parking on level ground is very important when checking the dipstick. My driveway is roughly on a 12 degree incline. In the Mazda, when parked uphill, the dipstick shows way over the full line. Park downhill and it shows way below the full mark. When I do a OC and put in the exact specified amount of oil then, park on level ground in the garage, the oil level is dead center.
On the Sienna, it shows different readings when uphill vs. downhill and the Matrix is also different from the others...
It all depends on where the dipstick tip sits in the pan relative to the centerline of the block. If you don't believe me, take a glass with some water hold it level and mark the outside. Now hold the glass at different incline/decline angles and image what happens if a dispsick tip sits in the front vs rear of the glass relative to centerline.
Unless you become familiar with your car's behavior there's no way to know how much the oil is off by looking at the dipstick.