It all depends on IF you want to lose weight.. to simply replace the same amount of calories that you burned off will leave you EVEN.... However, keep in mind that it really depends on the type of calories you eat.
As you might know, 300 calories of ALL carbs (e.g. potatoes) can raise your insulin level and therefore cause you to retain fat..(As Insulin acts as a fat block) Whereas, if you ate 300 calories of protein or even a complex-carb, then you might fair better.. I know some will say it's calories in and calories out, which yes, in very basic terms it is to some degree but not completely and therefore, I think it's more a matter of the type of calories you are consuming...
Your best bet, determine how much you want to weigh and then figure out based on that weight (and activity level) how many calories you can consume each day. Additionally, once you have a benchmark, then based on your own body, you can tweak your diet. Could be that you aren't as sensitive to processed carbs while others have difficulty..
There are two sites I like that are free.. one is myfitpal.com <<< on there you can determine your weight goals.. it will also require some tracking on your daily food and exercise.
Also, there is drmercola.com<<< on this site, he believes in eating specifically for your body type... again, could be your body responds well to more protein as oppose to starch.. on that site, they have you answer a bunch of questions ..
While there are different roads to weight loss, exercising and calories... I think what's important is to have an awareness of what you are eating each day. In my case, I keep a food journal... I find that when I do it (honestly) :) I actually lose more weight and stay on track..
Whatever you decide to do, best of luck to you!! :)