I think a budget that's going to work really depends on your family's size and lifestyle. A family with 4 kids is going to need a different grocery budget than a family with 1 kid. You have to look at your net income, then you start with your constants - your monthly fixed expenses. Ours looks like this:
Fixed Expenses:
- Mortgage
- Property taxes
- Property insurance
- Auto insurance
- Childcare costs
We have a fixed rate on our mortgage, so it's always the same monthly payment amount. I don't escrow my property taxes, so I estimate what they're going to be based on the prior year's taxes, and go about 8% higher (if I have money leftover there at the end of the year then that's just a bonus). Then I break that amount out monthly and that's my property tax budget for the month - it's a constant, but I take it out of my monthly income and physically pull that amount out monthly to a separate savings account so the $ is there at tax time. Same deal with property and car insurance. Childcare I pay automatically via online bill pay. But that's a fixed number too for my son's preschool.
Then it gets trickier for everything else. So I have a budget category for gas. And another one that I call food & dining, but is really a catch-all for everything else - stops to the coffee shop, a trip to Toys R Us, a new pair of shoes, ice cream for the kids, plus all of my grocery trips. Budgeting this way has REALLY helped me to understand where my money is going. I use the website mint.com to track my budget. Basically all of our credit cards and bank accounts are linked on there so that any purchase we make, be it a credit card purchase, debit card, check, or even ATM withdrawal, it shows up on the site. Then we "tag" the purchases by category and they show up in a really easy-to-read graph. I log on every day and check to see how much $ I have left in my food & dining category for the month...if I'm getting too close to the budget amount, I might skip that pedicure for now or cook the rest of the week instead of ordering out one night.
For medical or vet bills I just remove those expenses from the budget and they come out of our savings.