A grocery budget can get out of control fast, so it pays to be frugal. Without proper planning, an extra $100 or more can disappear from a monthly budget very quickly.

Here are some tips to help save some cash, along with some sanity, at the grocery store.

1. Don't shop for groceries when you are hungry.
It's just common sense, right? And yet, it's the most important thing when it comes to saving money and staying under budget at the grocery store. Going to the grocery store hungry will make everything look good, and therefore a necessity, causing you to spend more money than you should. Have a snack before you go, and your budget will be happier.

2. Always make a list.
Creating lists will not only help ensure that you don't find yourself back at the grocery store three days later because you forgot to get some eggs, but they will also lead you to exact points of the grocery store for the items that you need and help you to bypass the impulse items that you really don't need. Focus on the list and try not to diverge from it.

Along the same lines, try to cut the number of visits you make to the grocery store. Instead of shopping twice a week, shop for two weeks' worth of groceries at a time.

Why? One study says the average U.S. consumer spends more than $10 on impulse buys every trip to the supermarket. By cutting trips from twice a week to once every two weeks, you can save more than $500 a year on your bill and still get every item on your list.

3. See what's on sale.
Visit your favorite supermarket online before you head out and see what's on sale. You can often get great deals on items like low-sodium chicken broth. The American Dietetic Association suggests that since these have a long shelf life, you might as well stock up. Every week, check the frozen vegetable section and buy what's on sale so you always have a variety of mixed vegetables in the freezer.

4. Take a calculator.
Having a calculator allows you to keep a running count on how much you have left in your grocery budget. Remember to account for sales tax. Rounding up the prices to the nearest $.50, $.75 or $1 should help with this so you don't have to be too precise.

Also, remember that just because something is less expensive, it doesn't necessarily mean it's a better deal. For example, two boxes of pancake mix sit side by side, one is $2.50 and the other is $3. Don't just thoughtlessly grab the $2.50 one. Check the volume and use your calculator to determine the best value for your dollar.