That’s the beauty of it. After a few months you’ll know very close what they will be. And, you aren’t limited to what your budget is in those categories. Maybe your vehicle fuel bill is high one month because you drove out west to hunt. You can move money from another category to cover it. The point is that you shouldn’t be spending more than you make in a month, on average.
I’m sure it’s not for everyone, but for us, it was a game-changer. Financial stress has all but disappeared. We are contributing to retirement like never before. Paying CC on the day we get the statement, not the due date. And, we spend more, guilt free, on family vacations and fun stuff because we can look at the category and see that we have money dedicated to it.