Just a matter of degree

My new oven thermometer has already come in handy. I knew my oven couldn't be trusted, and now I have proof. Until now, whenever the oven timer would go off, I never rushed to check on whatever I was baking because I knew it wouldn't be ready. Nothing I baked in this oven was ever ready at the time indicated in the recipe. I figured that the actual oven temp must be lower than what the display indicated. I just didn't know by how much. My curiosity and (impatience over the drawn-out cooking times) finally overcame my inertia, and I bought an oven thermometer. I used it for the first time while baking lemon chicken yesterday. To get the temperature to 425˚, I had to set the oven for 465˚! And to my glee, the chicken was done at the time indicated by the recipe. Hooray! Have any of you checked your oven's temperature calibration?