Life isn't cheap after college. Here's what monthly expenses you can look forward to, and keep in mind you could spend more or less depending on your lifestyle:
Rent/Mortgage - If you have a roommate, you can probably get a two bedroom apartment for $800-1000, and cut your costs almost in half. Good luck finding a modest one bedroom apartment for under $600 a month. If you are smart enough to build up some equity, and can afford to buy a house you could end up paying over $1000 a month easily, so look to get roommates so that you can own and still afford it. Keep in mind that interest rates are dropping right now, and you don't have to put a down payment down. The only thing to consider is how sure are you that your job will be enjoyable and you will be there for at least a few years to let the house/property gain value. My advice: rent.
Renters/Homeowner Insurance/Utilities: Renter's insurance is so minimal I will not even take the time to discuss it. Homeowner's insurance is so much more on top of property taxes and all the little costs you don't think about: lawnmowing, fixing stuff that breaks, and more expensive utilities. My advice again, rent for at least a year so that you have the flexibility to move easily if the job doesn't work out or if you find out that there is a hot spot in the city where other young people live. Utilities will vary based on how big of place you have, so get a roommate if you have a large multi-bedroom place.
Vehicle - If you live in a large metropolitan area get a place close to your downtown office, and if your city has good public transportation you won't even need a car. For the majority of you, you will need your own vehicle. The cheapest option is to keep the car that you currently own. If it is your parents car, offer to buy it off of them so that you can get that pink slip and claim your very first asset out of college. It's a much cheaper option than buying a used or new car. I would recommend not just driving around a car that your parents still own. You want to be independent? Get the title, and remove yourself from your parents' expense column. If you are going to buy or lease a new car, do it within 3 months of graduation as many car companies have price cuts for graduates (Ford comes to mind). If you work for a large corporation there is a good chance that you will receive discounts with various manufacturers, so look into that. The cheapest route is to keep driving the car you already own, and the most expensive route is to finance a new car with monthly payments over $300-500 depending on the brand/model you go with.
Auto Insurance - This all depends on the company and your driving/criminal record. I have a clean record, but I'm driving a 2007 vehicle. Usually you can pay quarterly or bi-annually, but you can expect to pay a couple grand a year (I'm paying just under 2k) if you're driving a newer vehicle with full coverage and large medical/liabilities coverage on injuries you sustain or cause. One way to ruin yourself financially is to not pay for enough coverage, and then you are involved in a serious wreck a year or two after college that you end up having to pay out of pocket to cover for many years.
Health/Life/Dental/Vision Insurance - Some companies actually cover all of your insurance expenses, but most you will have to pay for out of each paycheck at a discounted price. There are usually different companies to choose from, but again, you're young and have a risky lifestyle so go with more coverage rather than less in case of a catastrophic injury that would put you in a hospital for awhile. I still haven't even used mine, but I plan on getting established with a local physician just in case. You can't afford not to have good insurance, so that you are more likely to be treated in more hospitals. I chose the top of the line plans, and I think I am paying less than $100 a month for everything.
Retirement/Savings - You should not pass up the 401K option that most companies provide. Most will match your contributions up to 4-6% of your entire paycheck amount. That's free money, so you might as well max out whatever percentage that they match. I donate 4%, my company donates 4%, and it's not a big deal if you just have it deducted out of your paycheck. I would also recommend getting a Roth IRA which is another type of long term savings account. There are different types of IRA accounts, but talk to any financial adviser or accountant and they will probably recommend the Roth because of some withdrawl and tax advantages. Investing now rather than later is very important simply because of the time value growth of money which is another way of say exponential growth. Go to any 401k calculator and play around. Saving $2000 a year is a great starting goal, and will result in a very large sum of money (nest egg) when you are 65 and ready to retire. I think the key is having it automatically deducted, so that I don't end up spending it on something that I didn't really need.
Fuel: Get an apartment or place close to work. Stop and go traffic in the morning and evening commute is horrible on gas mileage. You could spend $100 a month on gas or $300-$400 a month depending on what type of vehicle you drive and how far from work you live. Do you still think you look cool in that Tahoe or H2? I have a friend who had a suburban, and was spending $160 a week on gas last summer.
Food/Beverage: I grocery shop once every ten days or so, and spend around $70-80 each time. This usually includes cleaning supplies and toiletries which occasionally need replenished. I wish that was all I spent on food, but you will be going out to lunch quite a bit at work especially in the beginning with all of the cool networking events. I look forward to free lunches. If you are a bar lover on the weekends, buying a six-pack and pre-gaming helps to lower the night's expenses and is still acceptable after college. Stay away from buying rounds if you can, but some nights it just happens depending on the group you are with. Those are the nights where your friends at Visa or Mastercard help out.
Cell Phone, Internet, Television: $150 for an average cell phone plan, premium tv/dvr service, and hi-speed internet.
Those are the biggies. The rest of your money you end up spending or saving. Your choice.
