Congratulations, new grads! I see you out there, venturing out into the adult world with your diploma in your hand, wishing with every step that you'd spent a little less time studying calculus and a little more time learning exactly how to balance a monthly budget. So here's some personal finance for the my-parents-still-pay-some-of-my-bills set.
First Things First: Figure Out Your Regular Income
If you're lucky enough to snag a job right after graduating, you'll want to determine how much of that promised salary actually ends up in your bank account every month after taxes. There are a lot of individual variables (like your pre-tax contributions to healthcare or retirement accounts). If you want to get an accurate picture, you can plug your figures into a take-home pay calculator. Or just wait until your first regular paycheck. As a ballpark, you can assume Uncle Sam will take about a third of your salary before you ever see it.
Then: Add Up Your Expenses
To determine how much money you'll spend every month, figure out what ongoing bills you know you'll have to take care of by yourself (student loans, the phone bill now that mom's kicked you off the family plan), plus anything else you'll need to regularly spend money on in your post-grad day-to-day life (like, umm, groceries). You'll want to add up these expenses to determine how much of a chunk they take out of your take-home pay.
Don't Fudge Your Food Costs: The USDA publishes cost of food reports every month that reveal the average amount people spend on food at home weekly. Your numbers might vary from these, of course, but they offer a great guideline for how much to budget for what's probably your most uncharted expense.
If there are sections of your budget that you don't know yet, make a smart ballpark estimate and include those costs, too.
Make Sure You'll Make Rent: Personal finance experts suggest that you spend 30 percent or less of your monthly income on rent (not the take-home number, just your totally annual salary divided by 12). That's tougher to do in cities like SF and NYC, but still a great goal to work towards.
Add up all the expenses and subtract them from your take-home pay. If your expenses are less than your pay, you're in good shape (and can put the extra money towards building a savings account). If your expenses add up to more than you bring home, you'll need to make some cuts, like finding a cheaper place to live or downgrading your phone plan.
Once you establish your spending categories and how much you can afford to dedicate to each one, the tricky part is staying inside the lines month after month. You can't over-spend in one category without pulling money from a different one.