How far are you willing to drive to fill up on the cheapest gas?

With prices closing in on $3 a gallon once again, it's tempting to go out of the way, even shoot into the next town, to save a few pennies. But are you really saving if you do?

The financial Web site www.bankrate.com offers an online calculator to give you an idea of how far from home you can travel before you end up wasting more gas than you're actually saving at the pump.

To use it, you'll need to know the capacity of your gas tank, your fuel mileage rating and how much farther the cheap station is from your regular station.

Then plug in the per-gallon price at each station and click.

Depending on the spread, you can travel pretty far and still have the trip be worth it.

For instance, say you drive a Toyota Camry with an 18-gallon tank averaging 24 miles per gallon. According to the calculator, if you're saving 10 cents per gallon ($2.65 vs. $2.75) you can drive an extra 5 miles and still be ahead by a total of $1.23.

Of course, savings go up the bigger the price difference. If you are able to save 30 cents a gallon ($2.65 vs. $2.95) you can go 10 miles out of your way and still save a total of $4.17.

On the other hand, if you'll only be saving a few cents per gallon ($2.73 vs. $2.75) and plan to drive an extra 5 miles, don't do it. You'd be in the hole by 21 cents.

To go directly to the calculator, type www.bankrate.com/brm/calc/gasprice.asp.

Have fun plugging in different prices and distances. After all, it won't cost you a penny.